UC-NRLF
si?
THE LIBRARY
OF
THE UNIVERSITY
OF CALIFORNIA
PRESENTED BY
PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID
• A
LICE AND THEIR MENACE TO MAN
PUBLISHED BY THE JOINT COMMITTEE OF
HENRY FROWDE AND HODDER & STOUGHTON
AT THE OXFORD PRESS WAREHOUSE
FALCON SQUARE, LONDON, E.G. i
FIG. I.—PEDICULUS HVMANUS VAK. CORPORIS. Adult female, (x 4o.)
LICE
AND
THEIR MENACE TO MAN
BY
LIEUT. LL. LLOYD, R.A.M.C. (T.)
CHIEF ENTOMOLOGIST IN NORTHERN RHODESIA
WITH A CHAPTER ON TRENCH FEVER
BY MAJOR W. BYAM
R.A.M.C.
LONDON
HENRY FROWDE HODDER & STOUGHTON
OXFORD UNIVERSITY PRESS WARWICK SQUARE, E.G.
1919
Printed in Great Britain by R. & R. CLARK, LIMITED, Edinburgh.
*- ( t ira ^ u
PREFACE
THIS book is intended for the general reader
rather than for the specialist, and its chief purpose
is to introduce the main facts concerning the lice
of man which have been brought to light in the
last few years. It is somewhat amazing that,
though the louse lives in a closer association with
man than any other insect does, it should still
be the subject of so much erroneous information.
Even those who should have been best informed
knew little of its detailed habits, when the hard-
ships of war made it so necessary that means
should be devised for combating it. To-day we
are in a much better position to deal with it than
we were four years ago, and this is owing to the
closer attention which scientists have bestowed
upon it, often at great personal discomfort. In
this country its habits have been especially
studied by Professor G. H. F. Nuttall, of Cam-
bridge, and Mr. A. Bacot, of the Lister Institute
of Preventive Medicine, while in France Captain
A. D. Peacock, R.A.M.C., gave us much exact
information of its mode of spread among troops
in the field. These three workers also, with
M354457
viii LICE AND THEIR MENACE TO MAN
\
others, among whom may be mentioned especi-
ally Captain H. Orr, of the Canadian Army
Medical Service, and Captain J. T. Grant,
R.A.M.C., have devised means for reducing lice
in the armies. It is due, not to any fault in the
methods suggested, but to the excessive diffi-
culties of applying them under campaigning
conditions, that lice continue to exist among the
troops. Meanwhile many superstitions still sur-
round the insect, and an effort has been made to
dispel some of these.
Since Sir Patrick Manson, Sir David Bruce, and
Sir Ronald Ross first showed that insects could
play so important a part in the spread of diseases
much advance in knowledge has been made, and
it has been shown that malady after malady is
conveyed by them, until to-day we know that
insects are responsible for a large proportion of
the ills from which man suffers. It would have
been strange if the louse, this little pest which
shares our clothes and lives on such intimate
terms with us, had not been incriminated. In
the space of a very few years it has been found so
guilty that it now ranks with the mosquitoes and
the rat-fleas in its malign influences. Typhus,
one of the most dreaded epidemic diseases of man,
is entirely due to its activities. The same re-
mark applies to relapsing fever over the greater
portion of the world, including Europe and Asia.
This knowledge we owe to Doctor Nicolle and
Doctor Sergent and their co-workers. The im-
PREFACE ix
portance of their work, in this country at any rate,
has not received the recognition which it deserved,
probably owing to the absorbing interest of other
things which followed so soon after their dis-
coveries were made public. To most the ill
reputation of the louse remained still due to the
fact that it is a disgusting, irritating creature, a
symbol of filth, and not to the fact that its
presence is a very real danger to the community.
During the present year still a third disease,
trench fever, has been placed to its discredit, and
possibly even now the full extent of its guilt is
not known.
One of the most urgent sanitary problems of
the present and the future is therefore the destruc-
tion and prevention of lice. Now sanitary
problems concern not only the Medical Officer of
Health but each one of us, for it is only by
individual effort, working in harmony with public
regulations, that a really hygienic state can be
attained. This is especially true of personal
hygiene. Public instruction is therefore neces-
sary concerning lice, to correct the errors which
exist to-day and to disseminate the knowledge of
them which the last few years have produced.
Those who desire a fuller and more detailed
account of the habits of lice, and of the means of
combating lousiness, should refer to Professor
Nuttall's papers on the subject published in
Parasitology, Volumes IX. and X. Here also a
full bibliography of the subject will be found.
x LICE AND THEIR MENACE TO
I wish also to express my indebtedness to
Professor Nuttall for permission to reproduce
Figures 4, 7 and 8 from the work to which I have
referred.
LL. LLOYD.
HAMPSTEAD, LONDON,
October 1918.
CONTENTS
CHAPTER I
PA(iE
INTRODUCTORY . . 1
CHAPTER II
THE STRUCTURE OF THE Bonv-LousE . . .11
CHAPTER III
THE LIFE-HISTORY AND HABITS OF THE BODY-LOUSE . 21
CHAPTER IV
THE DISSEMINATION OF THE Boov-LousE AND LOUSINESS . 34>
CHAPTER V
DlSINFESTATION . . . . . .44
CHAPTER VI
THE HEAD-LOUSK (PsmcuLUS C'APITIS) . . .69
CHAPTER VII
THE CRAB-LOUSE (PHTHIRUS PUBis) . . .76
xii LICE AND THEIR MENACE TO MAN
CHAPTER VIII
PAGE
THE INCREASED MIGRATION OF BODY-LICE IN FEVERS . 84
CHAPTER IX
RELAPSING FEVER . . . . . .100
CHAPTER X
TYPHUS FEVER . . . . . .108
CHAPTER XI
TRENCH FEVER . . . . . .120
INDEX .
ILLUSTRATIONS
FIG.
1. Pediculus humanus var. corpons . . Frontispiece
2. Photograph of the Back of a Soldier showing the
Bronze Mottling often caused by Louse-bites . 8
3. Diagrammatic Section through an Adult Female
Louse . . . . . .13
4. Pediculus humanus laying an Egg on Hair . . 21
5. Egg of Body-Louse attached to Fibres of Cloth 22
6. Egg of Crab-Louse on Pubic Hair . . .22
7. The Larva of Pediculus humanus emerging from the
Egg . 24
8. Cast Skin of Body-Louse . . . .26
9. Fragment of Sewing-cotton fouled by Louse Excreta 31
10. The "Stammers" or Serbian Barrel . . .54
11. Improvised Disinfestor . . .56
12. The Crab-Louse (Phthirus pubis) . 76
13. Claw of Third Leg of Crab -Louse grasping Pubic
Hair ...... 77
CHARTS
I. Illustrating the Migration of Lice from an Afebrile
Man (P.H.) to an Afebrile Bedfellow (S.H.) . 95
II. Illustrating the Migration of Lice from a Febrile
Man (P.H.) to an Afebrile Bedfellow (S.H.) . 96
III. Illustrating the Effect of Fever on the Migration of
Lice ...... 98
IV. Curves of the Incidence of Typhus and Relapsing
Fever in the Second Roumanian Army, showing
the Association between two Louse-borne Diseases 107
CHAPTER I
INTRODUCTORY
THERE are two groups of insects to which the
general name " lice " is applied. These some-
what resemble each other in form and in the habit
of living among the hair or feathers of their hosts.
They are mostly small, pale insects, coloured in
various shades of white to brown, and are broad
and flat. The two groups are called the Mallo-
phaga, or biting lice, and the Anoplura, or suck-
ing lice. The Mallophaga have mouths with
which they are able to chew and eat the scales of
the skin and fragments of hair or feathers of the
animals they frequent. The majority of these
insects infest birds, and none of them are found
on man. They are all too familiar to those who
handle domestic birds, especially pigeons, and
though one may occasionally get on to a person
while he removes the feathers from a dead bird,
and may even bite at his skin, they never remain
on him. They cannot suck blood, but in heavy
infestation there may be raw surfaces caused on
the skin by their continuous nibbling. The
B
2 LICE AND THEIR MENACE TO MAN
Anoplura, on the other hand, have mouths so
modified that they are able to take only one form
of food, namely blood. This they obtain by
piercing the skin of their host and sucking at the
wound thus made. They do not eat one another
nor yet other insects, as an American doctor re-
cently stated they did, the form of the mouth
absolutely prohibiting this.
Some blood-sucking insects, such as the mos-
quitoes, horse - flies, and tsetse - flies, are very
catholic in their tastes, taking their meal from
any warm - blooded, and sometimes even cold-
blooded, animal which happens to be convenient
when they are hungry. Others, such as the
fleas, are more particular, being in general
confined to one or a very few different kinds
of animals, but .on occasion biting another sort
if they chance to get on to it. Thus when
a rat dies of plague its fleas leave it and may
happen to get on to man, on whom they will
feed and thus infect with plague, though they are
not normally associated with him. The human
flea, on the other hand, also normally infests the
badger. The sucking lice, however, are very
highly specialised and are rarely found on more
than one kind of host, though there are records of
the human body-louse being found on pigs and
monkeys. Such cases are almost certainly acci-
dental. This specialisation affects several char-
acteristics of the lice, such as the adaptation of
the grip of their feet to hair of a definite calibre
INTRODUCTORY 3
and the modification of their mouth-parts to skin
of a certain character and thickness. They are
also very sensitive to what has been aptly called
the climatic conditions of the skin, that is to say
its temperature and humidity. There are three
kinds of lice found upon man, the head-louse
(Pediculus capitis), the body- or clothes - louse
(Pediculus corporis, or Pediculus vestimenti, as
it is often called), and the crab-louse (Phthirus
pubis). It is with these three and mainly with
the second that we shall deal in the following
pages, and wherever " louse " or " lice " without
the prefix " head-" or " crab-" are mentioned, the
body-louse must be understood.
In reference to the systematic names of the
head-louse and body-louse, Linnaeus recognised
only one species, which he named Pediculus
humanus. His species was split up into P.
cor ports and P. capitis. Both Nuttall and Bacot
consider that these are merely racial varieties of
one species, so that the systematic names are
really P. humanus var. corporis and P. humanus
var. capitis.
Before the war the head-louse was the only
one with which the average person in this country
was at all acquainted. It occurs most frequently
on children, and they become infested occasion-
ally in even the best-regulated schools. The
body-louse was almost, though not entirely, con-
fined to the poorer, congested parts of towns and
to agricultural districts. In such places it was
4 LICE AND THEIR MENACE TO MAN
tolerably common. In mediaeval times it was
much more widely distributed, so that every one,
from the highest to the lowest, was all too
familiar with the pest, while it was accounted a
virtue in certain holy men that the lice swarmed
so thickly upon them uncontrolled. It was an
ostentatious manifestation of their humility that
they were unworthy to kill this, one of the most
disgusting products of creation. Like the spider
it took hold with its hands and was in kings'
palaces. Apart from references in literature we
have the evidences of " the scratching sticks ':
that in times past it was no shame to be lousy.
These were of various patterns, the handle being
about twelve inches in length and having at its
end a little carved ivory hand with the fingers
bent in a scratching position. It was a con-
venient implement to slip under the garments to
alleviate itching in otherwise inaccessible places.
As civilisation advanced and the frequent
changing of underclothing became a more pro-
nounced habit, body-lice became scarcer until
many people were unaware of the existence of
such an insect. The idea of lice became associ-
ated with that of dirt, and it was popularly
thought that only dirty people could become
lousy. The unfortunate who picked up a louse
in a tram or train treasured his secret in shame,
afraid to mention it to his closest friend. Worse
still, a person might become infested and feeling
the biting would look for a flea, never thinking
INTRODUCTORY 5
of making the closer examination of the cloth-
ing necessary to reveal lice. An unsigned letter,
evidently from a woman, recently related that
she had got into this condition and remained
infested for months until, thinking she was suffer-
ing from a skin disease, she consulted a doctor,
who revealed to her the cause of the trouble and
the remedy. An artisan informed us recently
that he had had lice upon him for three years and
had never even told his wife, who was doubtless
concealing the same condition from him. He
had become despondent about it, and as his
frequent changing of underclothing, baths, and
searches over his underclothing had failed to free
him, he had come to believe that the lice bred
from his skin owing to his weak state of health.
This sense of shame is a very grave mistake.
Lousiness is a disease as influenza is a disease, and
should be as readily confessed to. Its origin is
just as innocent, and though only people of
unclean habits in civil life can become heavily
infested, it is quite possible for a person with
the habits of an ordinary English household to
harbour a few lice over a very long period if
unaware of the simple methods necessary to
completely free himself.
Lice breed neither from the skin nor from dirt.
However unclean in habit a person may be,
unless he comes in contact with one who is lousy,
or picks up a louse which has left such a one, he
cannot become infested with them. In the time
6 LICE AND THEIR MENACE TO MAN
of the Pharaohs the idea seems to have prevailed
that dust could become lice. " And there were
lice upon man, and upon beast ; all the dust of
the earth became lice throughout all the land of
Egypt." The same belief was held by our
soldiers in the Boer War. After a wet night the
men would spread their blankets in the sun to
dry, and the heat would make the lice on them
become active and restless, so that what had
appeared to cursory inspection to be a clean
blanket had apparently become lousy owing to
its contact with the ground. Our troops in India
speak also of " ground lice " which appear among
them on the march and which they think originate
from the earth. In barracks with their cleanly
habits the men are almost free from lice and do
not notice the few. Under the harder conditions
of the march, when garments are less frequently
changed, these scanty lice increase and the men
notice their presence for the first time, hence
mistaking their origin. Lice hatch only from the
eggs of lice, and the eggs are always closely
cemented on to the hairs of the body or the
clothing.
The irritation caused by the bites of lice varies
much in different people. It is possible for a
person to become heavily infested and yet to be
quite unaware of his condition. This is especially
the case with the crab-louse. Immunity to the
sensation of the bite may be natural or may be
acquired after longer or shorter infestation.
INTRODUCTORY 7
Others are so irritated by the itching that they
will scratch away large surfaces of skin, leaving
bleeding wounds. Generally speaking, the bite
is less irritating than that of the flea or the bed-
bug, but to a few people, to whom the bites of
these are a matter of no account, louse-bites are
a source of real annoyance. This varying re-
action of different people to bites is general with
all blood -sucking insects. The first effect of a
bite is a small red mark, usually not raised, about
an eighth of an inch across. This usually dis-
appears and cannot be seen after an hour or so.
Later it may reappear and begin to itch, or it may
not be seen again. The actual bite sometimes
causes a slight pricking sensation if the wound
is near a nerve-ending. If a number of lice bite
near together the flushing of the skin may be
fairly extensive. Occasionally at the position of
each bite a small watery blister appears the
following day. After a day or two this collapses,
leaving a brown bronze scab, which persists for
days before it finally peels off. Bronzing of the
skin may follow the bites without any previous
blistering. By repeated and extensive biting
large areas of skin may be discoloured in this
way, becoming very dark and retaining the
colour for a long time. The condition into which
a person may be brought by this is shown in the
photograph (Fig. 2), which represents the back
of a soldier evacuated from France with trench
fever. The whole surface of the trunk was
8 LICE AND THEIR MENACE TO MAN
mottled over with bronze patches from the louse-
bites. This skin condition is sufficiently common
FIG. 2. — PHOTOGRAPH OF THE BACK OF A SOLDIER SHOWING THE
BRONZE MOTTLING OFTEN CAUSED BY LOUSE-BITES.
to have earned itself the name of " Vagabond's
disease."
The itching and the irritating movements of
the lice on the body may produce sleeplessness
INTRODUCTORY 9
with resulting neurasthenia. Scratching with
unclean fingers may cause the bites to suppurate,
and the multiplication of the sores may adversely
affect the general health. Lousiness is often the
cause of eczema in children with the consequent
serious glandular trouble. Lice have also been
shown to carry on their bodies the germs of
ophthalmia and no doubt contribute to the
spread of this disease. These malign effects,
though serious enough in themselves, do not
constitute by any means the real danger of lice.
In recent years it has been shown that three
serious epidemic diseases, typhus fever, relapsing
fever, and trench fever, are conveyed by them.
They have no direct connection with dirt or
famine, as was formerly supposed to be the case
with the first two. Without lice these diseases
would cease to exist throughout the greater part
of the world. Our own armies have fortunately
been spared the ravages of typhus and relapsing
fever during the present war, but have had a con-
siderable amount of trench fever, while prisoners
in the frightful prison camps of Germany have
in many cases been infected with the two former
diseases. We are therefore faced with the certain
introduction into this country of numerous
sufferers from one louse-borne disease and the
possibility of the introduction of two others.
In the absence of lice they would spread no
further. It therefore behoves us, for our own
safety and that of future generations, to wage a
10 LICE AND THEIR MENACE TO MAN
relentless war against the louse. This can be
done successfully by the efforts of public sanitary
bodies and by individual effort. The latter is a
very useful adjunct to the former, and indeed is
most necessary, and the public should be in-
structed in the danger of being lousy and in the
simple methods of cleansing themselves thor-
oughly. To this should be added the careful
and frequent inspection of school children, and
attention to the homes from which the infested
ones come. Much of this inspection is already
carried out with most beneficial results, but too
often the cleansed child is allowed to return to
the home where younger brothers and sisters or
even parents are in a similar verminous condition
and ready to reinfest them at once.
CHAPTER II
THE STRUCTURE OF THE BODY-LOUSE
THE louse is an elongated oval creature, varying
in colour from white to brown, while the red or
black colour of the blood in the gut can be seen
through the skin. When young and newly fed
it appears to be bright red and is then known
in the soldier vocabulary as a " red-back." As
the blood becomes darker in digestion it is called
a " black-back " or " grey-back " and is often
thought to be a different kind. The full-grown
female louse measures about one-sixth of an
inch in length and one-fifteenth of an inch in
breadth, while the newly hatched one is about
the size of a pin's head, all intermediate stages
existing. Its skin is leathery, and it is not very
easily crushed, except when quite young or just
after it has " cast its skin." It is covered all
over with a smooth coat of a substance known
as chitin, which corresponds to the dead horny
layer of our own skin. It is sparsely covered
with fine hairs. In the young stages a fresh
layer of chitin grows under the old layer, which
12 LICE AND THEIR MENACE TO MAN
splits and allows the louse to creep out. It is
naturally very soft when it first emerges from
its old skin, and is white and semi-transparent.
It soon hardens and takes on in parts a sepia
tint, which varies much in density, being darker
on the lice which infest dark-skinned races.
Often it appears to have a sepia-coloured border
running all around the edge of its body.
In the following description of the adult louse
reference should be made to Fig. 1 and to Fig. 3.
The latter is a diagram representing some of
the more important organs of a female louse
which would be s'een if the insect were cut clean
down the middle line and one half removed.
Where an organ is paired, only those of the right
side of the body are thus represented.
The body is divided into three regions, the
head, the thorax, and the abdomen. The head
is attached to the thorax by a very narrow neck
and has a considerable power of independent
movement, up and down and from side to side.
Between the thorax and abdomen, at the waist,
there is hardly any constriction at all. The
head is rather pointed in front and rounded
behind. It bears at the tip, and just below it,
a circular opening, the mouth, which is surrounded
by a ring of pliable tissue, the haustellum, which
bears a number of hooks (Fig. 3, 1). At the
sides of the head are attached the antennae
or feelers, which are composed of five joints.
The antennae bear hairs which have a sensory
STRUCTURE OF THE BODY-LOUSE 13
14 LICE AND THEIR MENACE TO MAN
function, of which we know nothing definite except
that they guide the movements of the insect.
Behind the antennae are the black eyes, which
are simple, in contradistinction to the eyes of
higher insects such as the house-fly, the eyes of
which are compound and made up of many
elements, to each of which the simple eye of the
louse corresponds. The latter is probably able
to see no more than is necessary to enable it to
distinguish shades of light. The thorax narrows
from behind forwards and bears the six legs.
The legs are jointed and end each in a single
large claw which has a slightly serrated edge ;
the first pair being larger in the male than in
the female. The claw has a similar movement
in relation to the rest of the leg as the blade of
a penknife has to the handle, but does not close
so completely down on it. In the space between
claw and leg hairs or fibres are gripped tightly
by the insect when it is walking, and it is by
means of them that it clings to cloth and hair
even after death. There are never any wings,
and the louse is quite unable to jump. The
abdomen is divided into a number of segments
by means of slight constrictions at the sides
and rings round the body which can be faintly
seen. In the adult female the abdomen is
broader and heavier than in the male, while the
tip turns slightly down and is slightly forked.
In the male it is more barrel-shaped, cylindrical,
and the single-pointed tip is turned up. The
STRUCTURE OF THE BODY-LOUSE 15
anus is at the end of the body, and just below it
lies the genital opening. In the female this is
a wide pouch, and in the floor of this are a pair
of stout peg-like organs the tips of which over-
lap and which work against one another like a
pair of pincers, gripping the hair or fibre of cloth
on which the egg is being laid. These are called
the gonopods (Fig. 3, 18). The copulatory organ
of the male is a kind of bag which when at rest
is inverted inside the body. On this is a strong
pointed organ and a small inconspicuous penis.
The former organ can be easily seen through
the skin of the lower side, lying near the end of
the body.
To turn to the digestive system : the mouth
has no biting jaws, but in its lower part is situated
a long very sharp stylet which cannot be seen
when it is retracted inside the head. This stylet
(Fig. 3, 2), or stabber as it is usually called, is
formed of three long elements which are attached
parallel to each other in such a manner that they
form a tube with an extremely fine bore. It is
with this hollow stabber, which can be thrust
out of the mouth opening, that the louse makes
the wound in the skin when it feeds. The
mechanism of feeding is described elsewhere.
Above the stabber a short broad tube leads out
of the mouth into a chamber, the pharynx
(Fig. 3, 3), which has muscular walls and which
is the sucking pump. From this a long very
narrow oesophagus (Fig. 3, 4) runs to the fore-
16 LICE AND THEIR MENACE TO MAN
gut (Fig. 3, 5), which is a wide tube and corre-
sponds to the stomach of higher animals. It
has two capacious pockets (Fig. 3, 6) which lie
one on each side of the oesophagus and seem to
act as storage chambers for the blood, which can
be seen in them with the naked eye through the
body wall of the louse. The walls of the gut
contract and expand in waves, causing the con-
tents to flow backwards and forwards and to
keep circulating so that they are thoroughly
mixed with the digestive juices and come con-
tinually in contact with the wall, where the
nutriment is absorbed. These peristaltic move-
ments are a very noticeable feature in the louse,
in which insect the width of the gut in propor-
tion to its length is exceptional. Most insects
have the gut narrow and the necessary absorptive
surface is obtained by an increase in the length,
the gut being thrown into many coils like that
of a mammal. In such a gut the food passes
fairly continuously backwards, absorption pro-
ceeding as it moves. In the louse it moves to
and fro, and by this means the same effect is
obtained with the wide short gut. The fore-gut
narrows behind to form the hind-gut (Fig. 3, 11),
which runs forward again, forming an S-shaped
loop. Into this open the four long thin tubules,
the Malpighian tubes (Fig. 3, 10), which are
supposed to function as kidneys, to pass into
the gut waste products, which thus find their
way to the exterior. Farther back the hind-gut
STRUCTURE OF THE BODY-LOUSE 17
becomes the rectum (Fig. 3, 13), on which is a
swollen portion or ampulla (Fig. 3, 12), which
has a thick wall and apparently expels the faeces.
The rectum opens to the exterior at the anus
(Fig. 3, 14), which is at the end of the body.
There are two pairs of salivary glands, which
are always prominent organs in insects, their
secretion having a wider scope than that of the
organs of the same name in mammals. One
pair are trouser-shaped (Fig. 3, 7) and lie on the
fore-gut, closely attached to its surface. The
other pair are kidney-shaped (Fig. 3, 8) and lie
on either side of the oesophagus. Each of the
four is connected with the pipe of the stabber
by means of a very fine duct (Fig. 3, 9), which
carries away the secretion.
The nervous system consists of three central
masses, from which the nerves run to the various
organs they serve. These are, firstly, a large
mass or brain (Fig. 3, 15) which lies in the head
above the oesophagus ; secondly, a smaller mass
(Fig. 3, 16) lying below the stabber base and
connected with the brain by means of a nerve
cord on each side running round the gut ; thirdly,
a large mass (Fig. 3, 17) lying in the thorax below
the gut, and from which nerves run to the legs
and backwards into the abdomen. This third
mass is connected by a nerve cord with the
second.
The louse, like all other insects, breathes
through a system of tubes, or tracheae, which are
c
18 LICE AND THEIR MENACE TO MAN
really ingrowths from the skin, so that the inside
of the tubes is part of the outside of the body.
This system opens to the exterior by means of
small pores called spiracles which are situated along
the sides of the body on the thorax and abdomen.
The spiracles are round and are protected by
a ring of teeth which filter the air and prevent
gross particles entering. Nor can water enter
owing to its high surface tension, but fluids, such
as oils, which have a lower surface tension than
water are able to enter and thus clog up the
pores and choke the insect. Each of the spiracles
is connected by means of a short passage with a
horse-shoe-shaped tube, the curve of which is
towards the hinder end of the body. From this
branching tubes run and ramify right through
the body of the insect, forming a network over
all the organs, so that no part is left without a
supply of air. The system has thus not only
the function of our lungs but also one of the main
functions of our circulatory organs. Air is forced
in and out of the system by contraction and
expansion of the body wall with a bellows-like
action.
There are no circulatory organs in insects as
we know them in higher animals, and no true
blood. The main function of these is taken on
by the respiratory system described above. The
nutriment from the gut is carried about the body
by the fluid of the body space, or haemocoele,
which is a cavity extending all through the insect
STRUCTURE OF THE BODY-LOUSE 19
even into the hollows of the main hairs. In this
fluid are cells corresponding to the white corpuscles
of the blood of higher animals, but none corre-
sponding to the red corpuscles. This fluid is kept
circulating by means of an open contractile tube
which is, for convenience, called a "heart," and
which lies above the gut. Such an organ remains
to be described in the louse. The extensive con-
tractions of the gut mentioned above will aid
materially in the circulation of the coelomic
fluid.
The internal organs of generation of the female
louse consist of a pair of ovaries, where the eggs
originate and grow, and a tube connecting these
with the exterior. Each ovary (Fig. 3, 23) is
made up of a bunch of five tubes which look like
strings of sausages in which each sausage is much
larger than the one in front of it. The swellings
which give them this appearance are due to the
growing eggs inside. The oldest egg is near the
base and the youngest one is near the tip in each
tube. As the eggs become fully developed they
pass one after the other (Fig. 3, 22) into the
central tube or oviduct (Fig. 3, 21). Here the
egg receives the mass of cement (Fig. 3, 20)
which surrounds its base when it is laid and fixes
it on to the hair or cloth to which it is attached.
The cement is poured into the oviduct from the
large glands (Fig. 3, 19) which secrete it. It is
probable that the eggs are fertilised while in the
oviduct, but there is a little gap in our knowledge
20 LICE AND THEIR MENACE TO MAN
here. A short vagina leads to the exterior from
the oviduct.
The internal male organs consist of a pair of
testes, each of which is in two parts. Each testis
is connected by a fine tube with a wide seminal
vesicle which meets its fellow at the base, where
the two pass off into a narrowing duct which
carries the male elements to the penis and so
into the female during coitus.
The remainder of the body space is filled up
by the muscles and the cells of the fat body.
The latter is highly developed and serves to store
the food among other functions ; but the detailed
physiology of insects is not well known, and it
would be useless here to describe special cells
and attempt to ascribe to them functions largely
hypothetical.
CHAPTER III
THE LIFE-HISTORY AND HABITS OF THE
BODY-LOUSE
Development. — The eggs or nits of the body-
louse are laid attached to fibres of cloth or some-
times to the hairs of the body. In shape the egg
(Fig. 5) is ovoid, about one-twenty-fifth of an
inch in length, with rather straight sides, and
closed at the top by means of a cap or operculum
FIG. 4. — PEDICULUS HUNANUS LAYING AN EGG ON HAIR. The gono-
pods (gon.) grasp the hair and direct the alignment of the egg.
(After Nuttall.)
which is sculptured over part of its surface by
a circular area of small nodules. It is firmly
fixed in position by a hard cement which sur-
rounds the base of the egg and the strand to
which it is attached. According to Nuttall (1)
the female louse in ovipositing grasps the fibre or
hair on which it is laying the egg by means of its
gonopods (Fig. 3, 18, and Fig. 4), and by this
22 LICE AND THEIR MENACE TO MAN
means orientates the egg so that the cement flows
round the particular anchorage with which it is
dealing. If this should be a hair the result is
that almost invariably the egg lies with its axis
parallel to that of the hair and consequently it
FIG. 5. — EGG OF Bony-LousE ATTACHED FIG. 6. — EGG OF CRAB-LOUSE
TO FIBRES OF CLOTH, (x 50.) ON PUBIC HAIR, (x 60.)
is less liable to be dislodged. The eggs are gener-
ally laid in clusters, for there is a well-marked
tendency for the insect to return to the same spot
to lay, though it may wander far in the mean-
time. The egg is white in colour and has a
pearly sheen. It is rather translucent when
LIFE-HISTORY OF THE BODY-LOUSE 23
newly laid, but becomes more opaque later as the
young louse develops inside it. The empty shell
is hard and brittle and remains attached after
the louse has emerged ; the top fraying away, but
the base and cement remaining. On the bristles
of brushes the empty shells of the eggs of the
hog-louse (Haematopinus sui) are sometimes seen
in large numbers. They are of course harmless
in themselves, but are unsightly, and at any rate
afford evidence that the cleaning of the bristles
has been none too thorough.
It is difficult to tell whether the egg is empty
or full without the aid of a lens. At the tempera-
ture which ordinarily exists between the skin and
the clothing the eggs hatch in from seven to ten
days, but if kept in a cooler atmosphere the
incubation period is lengthened. Thus when a
garment is put off at night hatching is retarded
in proportion to the coolness of the bedroom.
It is not essential to the hatching of the eggs that
the garments which hold them should be worn,
as the young will emerge if they are incubated at
any temperature above 72° F., and below that
which destroys them, provided that the air is not
too dry. At temperatures below 72° F. the
young will not emerge. Nuttall (1) describes the
hatching of the egg. The inside of the shell is
like that of a deep smooth chalice, and the young
louse completely fills it and has its legs folded
back along its body. The mechanism of its
emergence is remarkable. Air passes through
24 LICE AND THEIR MENACE TO MAN
the cap and is taken in by the insect at the mouth
and passed out behind it. As this increases a
growing cushion of air is formed in the bottom
of the shell which pushes the louse forward as a
bullet is pushed out of a rifle, though the move-
ment is slow. The head pressing against the
cap thrusts this up and the louse comes into the
world like a jack-in-the-box until its front legs
are free and it can grasp surrounding objects and
puU itself out (Fig. 7).
FIG. 7. — THE LARVA OF PEDIGULUS HUMANUS EMERGING FROM THE EGG.
The louse passes air through its body into the shell behind it and
thus blows itself out until it can grasp surrounding objects and
draw itself free. (After Nuttall.)
The newly emerged louse is white and fragile.
Under ordinary circumstances it feeds within the
first hour of its active life and then looks like a
bright red speck and is very conspicuous. Unless
able to feed within the first twenty-four hours of
its life it dies. From the first it is easily recognis-
able for what it is, being much like its parents.
As a comparison, the larva which emerges from
the egg of a flea is a small white active grub,
nothing at all like the adult, which runs about on
LIFE-HISTORY OF THE BODY-LOUSE 25
the ground or in the nest of its host feeding on
organic debris. When this is full-grown it spins
a cocoon, inside which it turns into a resting stage,
the pupa, which is in shape somewhat like the
adult flea but is white and soft. Inside this pupa
the adult is formed, and from the cocoon emerges
the brown familiar flea. Such a development is
known as a " complete metamorphosis." The
development of the louse is by >; incomplete
metamorphosis " ; that is, the food and form of
adult and young are similar and there is no
resting stage. The growth, however, is not a
continuous unbroken process like that of a man,
but takes place in a series of three jumps, each
represented by the casting of the old chitinous
covering and the development of a new and
larger one. Chitin is not a very elastic substance
where it is thick, and so this moulting process is
necessary to enable growth to take place. Crabs
and lobsters grow in the same way by casting off
the old coat, which will not stretch, and develop-
ing a new one, and the soft dog-crab which has
just moulted is a familiar object on the sea-
shore. The young louse moults for the first
time when about two days old. The skin splits
along the back of the thorax, along the neck and
the top of the head. The insect then expands
and forces up its back, draws out its head and
legs and then pulls itself free of the old skin
(Fig. 8), which remains attached to the cloth.
It is a flimsy object very easily seen on a lousy
26 LICE AND THEIR MENACE TO MAN
garment. In this process not only the outer skin
is cast, but also the inside of the mouth with the
stabber, and the main tubes of the tracheal
system. The insect which emerges is now called
a nymph, or sometimes second-stage larva, and
is more robust than the first-stage, but is other-
FIG. 8.— CAST SKIN OF BODY- LOUSE. (After Nuttall.)
1. Eye. 3. Stabber.
2. Antennae. 4. Claws, incurved to grasp cloth.
5. Spiracles.
6. Tracheae.
wise much like it. At the end of two or three
days it moults once more in the same manner
and becomes the second-stage nymph or third-
stage larva. After the elapse of about three
days more it moults for the third and last time,
and is now an adult. The adult louse is rather
less barrel-shaped than the earlier stages and
shows the external evidences of its sex for the
LIFE-HISTORY OF THE BODY-LOUSE 27
first time. From the time of hatching to its
becoming full-grown the louse under the most
favourable conditions occupies about eight or
nine days. Allowing a period of eight days in
the egg, we see that from the time that the egg is
laid to the time when the louse is ready to begin
breeding there is a period of about seventeen
days. This obtains only when the louse is in
continual contact with the body, and is prolonged
by adverse conditions, such as its cooling at night
owing to the putting off of garments.
Feeding. — Under normal conditions the louse
feeds about four to six times a day, preferring to
do so when its host is at rest, sitting or sleeping.
It does not leave the clothing and creep on to the
body to feed. All that is necessary is for it to
be able to touch the skin with its mouth. If lice
are put on to small fragments of cotton and these
on to the skin, they will be seen to feed in all
positions, some at right angles to the surface,
and some even with their backs to it, the head
being thrown backwards till the mouth touches
the skin, while the legs feebly grip the cotton or
even wave in the air. For this reason lice bite
mostly those parts of the body, such as the hips,
shoulders and neck, and fork of the legs, where
the garments press closely against the skin, and
avoid more the parts where the clothing is slack.
Soldiers who wear body-belts often find that they
are intensely irritated by bites in this locality.
This habit of not leaving the clothing to feed is
28 LICE AND THEIR MENACE TO MAN
distinctly advantageous to the louse, since man
scratches at his skin and not at his garments,
and if he feels the movement of the louse he
instinctively feels on the skin for it and not on
the clothing over the spot where he felt it move..
The only purchase which a louse needs for feeding
is the grip given by the teeth which are on the
haustellum, and this purchase is the fulcrum
against which the stabber works. The haus-
tellum around the mouth, being closely pressed
against the skin, forms a circular air-tight cushion,
and into the area thus enclosed the stabber is
forced down into the tissues. Salivary juice
now flows down the hollow stabber into the
wound, and as this acts a slight pink flush may
be seen around the position of the bite owing to
the increase in the blood at the spot caused by
the action of the fluid which is being injected
and which also retards the clotting of the blood.
The salivary juice is thus mixed with the blood,
not in the mouth but in the tissues of the person
on whom the louse is feeding. This is a vastly
important fact in connection with the trans-
mission of disease by many blood-sucking insects,
since the fluid has become the conveyer of the
infection. The virulent organisms of malaria
and of sleeping sickness are thus injected into
man by the insects which carry them by means
of the salivary juice. It is possible that the
typhus infection is conveyed by the louse through
the same medium.
LIFE-HISTORY OF THE BODY-LOUSE 29
To return to the feeding louse : there is a
pause while the salivary juice acts on the blood
and then sucking commences. In one in which
the chitin is fairly transparent the pumping
pharynx can be seen expanding and contracting
with a rapid movement which is almost a flicker,
and the blood can be seen collecting in the gut.
At the same time waves of contraction are seen
to pass along the alimentary canal. The louse
is a slow feeder and may occupy half an hour or
more in completing its meal, and it is rarely that
it finishes in under fifteen minutes. This slow
feeding is unusual in blood-sucking insects, but
is more than paralleled by the African tick
(Orniihodorus moubata), which has the nocturnal
habits of the bed-bug, and often occupies two or
three hours over its meal.
Of blood-sucking insects those which cause
most pain by the actual operation of biting are
the flies belonging to the genus Tabanidae : the
horse-flies, chegs, blind-flies, etc. These insects
alight on the skin and with their powerful jaws
make gashed wounds from which blood flows.
This they imbibe quickly, and the wounds often
continue to bleed after they have left. It is not
often that such an insect obtains a full meal from
a man at the first attempt, as he strikes at once
at the position of the bite if his hands are un-
occupied. In these cases, however, there is
usually no subsequent irritation from the bite,
so that the salivary juice, if such is injected, has
30 LICE AND THEIR MENACE TO MAN
no poisoning effect, or the nature of the wound
made may obviate the necessity for its injection.
Insects such as mosquitoes and fleas*, if they do
not draw blood at once from the place they choose,
move quickly and try in another spot ; but the
louse very rarely does this, generally waiting
patiently for the blood to collect. It is essential
that such an insect should cause little pain during
the actual process of feeding, so as not to attract
the attention of its host to its ultimate cost.
The blood when recently taken in shows very
distinctly red in the gut, but soon takes on a
black colour owing to the action of the digestive
juices. As the feeding louse approaches repletion
it usually begins to defaecate. It is a wasteful
feeder, and sometimes blood almost unchanged
can be seen passing out of the anus while it is
still gorging itself. The excreta has been shown
to be of very great importance in relation to the
disease-conveying capacity of the insect. The
amount passed is considerable, a well-fed adult
louse excreting as much as seventy to eighty-five
granules a day. It is sometimes ejected in rough
masses and sometimes in a long spirally coiling
thread, or again in a fluid condition which quickly
dries up. In bulk, for in experimental work it
can be collected in surprisingly large quantities,
it has the appearance and colour of finely ground
coffee. Under the microscope it is seen to con-
sist of rough black granules and smooth red
pieces. It is very easily blown about and can be
LIFE-HISTORY OF THE BODY-LOUSE 31
carried by the wind. On the garments of a
lousy person the excreta may be seen stuck on to
fibres of the cloth, especially about the patches
of eggs, than which they are more conspicuous
and which they may sometimes serve to indicate.
Fig. 9 is a drawing of a fragment of sewing-cotton
which was removed from one of the experimental
boxes of lice. The masses and fragments of
excreta may be seen on it. The larger masses
all ultimately break up into fine granules. In
the armpits of infested men dirty brown patches
FIG. 9. — FRAGMENT OF SEWING-COTTON FOULED BY LOUSE
EXCRETA, (x 30.)
are often seen where these louse faeces have dis-
solved in the sweat.
Breeding. — The female louse commences to lay
eggs on the second day after the last moult. She
does this whether she has been fertilised by the
male or not, but only if she has been fertilised
will the eggs hatch. Copulation takes place fre-
quently, and in the operation the male creeps
underneath the female and the genital openings
are placed in apposition. Nuttall (2) has recently
described the process in detail. The female
pouch is held open by means of the pointed
chitinous organ of the male which is known as
the dilator and which can be seen through the
32 LICE AND THEIR MENACE TO MAN
skin of the lower surface of the body. The
inverted bag of the male is now everted, rolling
inside out into the vagina of the fernale, and the
spermatozoa pass through the small penis, which
is thus thrust well into the vagina, and fertilisa-
tion is effected.
The eggs are laid at the rate of eight to ten a
day, and this continues for twenty-five to thirty
days, so that each pair of lice produce about three
hundred offspring of the first generation, and
many of these will have started to breed before
their parents die. Bacot (3) states that a female
louse under conditions ideal from her point of
view might have about 4000 offspring during her
lifetime. Conditions would of course never be
ideal. Some of the eggs wrould probably fail to
hatch, and many of the young would die from
one or other of the many catastrophes which are
liable to befall the louse. As an actual instance
of breeding capacity the following may be quoted.
Into one of the small experimental boxes used in
the laboratory a hundred young larval lice were
placed. The box was about three-quarters of an
inch in diameter and of the same depth. It had
a glass bottom, while the other end was covered
with chiffon, through which the lice could not
escape but could easily feed. The insects were
fed twice daily by being bound on to the forearm
for half an hour for each feed. Between their
meals they were kept in an incubator at a tempera-
ture of 86° F. After forty days the box was
LIFE-HISTORY OF THE BODY-LOUSE 33
opened for the first time. It was full of lice,
alive and dead, and the cast skins, which, together
with the piece of flannel contained in the box,
formed a compact mass ; 507 living lice of various
ages were counted, while there were innumerable
eggs. The conditions had of course been by no
means ideal for the lice, for it was difficult to
understand how they had been able to move
about in the confined space.
Death. — Death is of course usually accidental
owing to crushing or starvation as the result of
the louse losing contact with its host, either
through the putting off of the garment containing
it or to its own wandering. The average life of
a louse which does not meet with one of these
accidents is from forty to forty-five days ; a very
short period compared to that of a flea, which
may survive a year. Towards the approach of
death the louse becomes very thin and anaemic-
looking. It ceases to breed or feed, and may
continue to exist for several days in this senile
condition before death overtakes it.
REFERENCES
(1) NUTTALL, G. H. F. "The Biology of Pediculus humanus,"
Parasitology , vol. x. pp. 80-185.
(2) NUTTALL, G. H. F. "The Copulatory Apparatus and the Process,
of Copulation in Pediculus humanm-" Parasitology, vol. ix. pp.
293-324.
(3) BAOOT, A. "A Contribution to the Bionomics of Pediculux
humanus (vestimenti) and Pediculus capitis," Parasitology, vol. ix.
pp. 228-258.
n
CHAPTER IV
THE DISSEMINATION OF THE BODY-LOUSE
AND LOUSINESS
Dissemination. — A problem which faces every
animal and plant is how it shall distribute itself.
Each is always seeking new worlds to conquer ;
each is to itself the most important thing in
creation ; each has the ambition, latent or
obviously expressed, to inherit the earth.
Except for this tendency to migrate any in-
dividual species in a given locality would tend
to choke itself out by exhausting the food supply.
This is, in fact, going on around us every day.
The organisms of a disease enter the human
body and multiply enormously till at last their
host dies of exhaustion or their poisonous effect,
and the parasites die with their host unless the
death is merely their means of distribution. It
is not the racial ambition of any species to
exhaust its food supply, or for the parasite, except
in special and exceptional cases, to kill its host,
a proceeding which would ultimately lead to its
own destruction. Parasitic insects have solved
DISSEMINATION OF BODY-LOUSE 35
the problem of distributing themselves in a vast
variety of ways. Some, such as the bot-flies,
are in one stage immobile parasites, and in
another active flies which are able to seek out
and place their eggs on a fresh host. Some,
such as certain species of the hippoboscid flies,
which have a louse-like habit, are able to fly in
one stage and cast their wings, for which they
have no further use when they reach their fresh
prey. Certain species of fly, the maggots of
which live in the skin of mammals, have become
still more ingenious and lay their eggs where a
mosquito may accidentally pick them up and
carry them to another mammal. There are
others, to which group lice as a whole largely
belong, which rely more on the habits of their
hosts for their dissemination rather than on any
active habits of their own. If man radically
changed his habits in one or two particulars his
body-lice would cease to exist. This has already
been indicated in the history of civilised countries,
for it was the growing habit of constantly chang-
ing underclothing and paying more attention
to the toilet that reduced body-lice to so small
a frequency before the War. Now that stress of
circumstances has caused many millions of people
to revert in these respects to the habits of
mediaeval times, lice have come into their own
once more.
The spread of lice is due, to some extent, to
their own active habits, for when their host is
36 LICE AND THEIR MENACE TO MAN
in warm surroundings, so that- the temperature
outside his clothing approximates to that inside,
they are liable to migrate from him and pass
on to another near. This takes place especially
in beds where two people are sleeping together
(see Chapter VIII.). To sleep with one who is
infested with lice is a certain means of becoming
verminous. Lice, as will be shown later, are
also liable to leave their host when the skin
becomes too hot for them, as when he is in a fever.
They also leave at his death and scatter over his
bedclothes and surrounding objects, and are very
likely to be picked up by any one coming in
contact with these. They may be dislodged by
brushing and fall to the ground, and it has been
stated that they have been blown off by the
wind and carried to a distance. They may also
of their own accord leave discarded garments.
Lice spread abroad by any of these means
may be termed stray lice, and they are in a very
helpless condition for finding fresh prey as com-
pared with the human flea or the bed-bug. The
flea jumps into the air when disturbed by a sudden
draught of wind, such as is caused by a foot
moving near it, and grasps anything it meets
with in its course, thus finding its temporary
host. The hungry bed-bug hunts down its
victim, probably guided by his scent, often
travelling long distances to find him. The stray
louse can only wait till a fresh host comes in
contact with it, or wander aimlessly about on
DISSEMINATION OF BODY-LOUSE 37
legs not very well adapted for travelling on
anything except rough cloth or hair. Peacock (1)
showed that it is improbable that they are
attracted to man in any way by his smell, since
they took no notice of a sweat-impregnated
shirt placed near them. They are guided in
their movements, to some extent, by a sensitive-
ness to light. When well fed they creep into
dark places, but hunger drives them towards
the light again. This habit, however, helps them
little in their search. They are very sensitive
to heat, being adapted to the temperature which
exists between the skin and the clothing. 86°-
90° F., and what guidance they get in finding
a new host they probably obtain from this faculty
alone. Stray lice in a bed very quickly find a
man who sleeps in it. The temperature of their
surroundings has a profound influence upon
their movements and vitality. At 104° F. they
are extraordinarily active, running round and
round with the rapidity of bed-bugs. At 90° F.
they are moderately active, and if unable to feed,
digest what food is in them and succumb about
the second day from starvation. At the tempera-
ture of a warm room, about 70° F., their activity
is little marked, and their vitality is so reduced
that they may survive a week without food. At
still lower temperatures they become moribund
and die slowly, some having been known to survive
ten days at the freezing-point, and this is the
longest period which lice have been known to live
38 LICE AND THEIR MENACE TO MAN
without food (Warburton). While they remain
active the distances that they are able to travel
are somewhat surprising, their movements though
slow being fairly persistent. A well-fed female
louse was observed to walk along a stretched
thread of cotton for a distance of four feet in
thirty minutes in a warm room, the impulse to
walk being given by placing it on the end of the
thread near the window. Peacock observed two
travel a distance of five feet in an hour where
they had apparently no particular stimulus to
guide them. By such wanderings the louse is
no more likely to find a fresh host than by
remaining where it happens to fall. If it is on
a smooth surface, such as a board, and a cloth
surface brushes over it, it immediately attaches
itself to the cloth. The author has occasionally
made use of this habit when lice have accidentally
fallen on the laboratory floor by passing a Turkish
towel over the place where they fell and at once
recovering them. Again, if the insect is on a cold
cloth surface and a warmer one is pressed against
it, it will immediately leave the former for the
latter. In this way lice may be picked up in
public conveyances with cushioned seats. As
these chances do not happen very often it is
certain that the vast majority of stray lice die
without finding a new host. The more con-
gested the community the more likely are they
to be picked up. It also follows that when lice
are on a discarded garment the best chance for
DISSEMINATION OF BODY-LOUSE 39
them is to remain where they are in the hope of
the article being again worn. This is what the
majority do, though, as mentioned above, a few
are prone to wander. A stray louse, when it
finds a new host, can, of course, only multiply if
it happens to be a fertilised female. A male
or an unfertilised female would die without pro-
ducing young. A single louse, however, is enough
to cause an attack of a louse-borne disease,
should it be an infected one, and we have a
record of an officer who received a single louse
upon him, scratched himself, and in due course
developed trench fever.
An unoccupied dwelling cannot be infested
by lice in the manner in which it may be by
bed-bugs or fleas. The presence of lice denotes
recent occupation, and after it has been vacated
for ten days it may be considered as absolutely
safe. Peacock (1), who studied the dissemination
of lice among our troops in France, discusses in
detail the reputation which certain dug-outs get
of being lousy. He comes to the conclusion that
this is due to the presence of infested men and
not to any inherent quality of the habitation.
The ones with the worst reputation were the
largest ones in which most men congregated.
Bedding, however, is a most important source
of spread, and it is courting disaster to sleep in
that recently used by an infested person. Most
convincing figures in proof of this are quoted by
Nuttall (2). Dr. Hamer of the London County
40 LICE AND THEIR MENACE TO MAN
Council caused the beds in some common lodging-
houses, which were largely used by people of
the tramp class, to be examined weekly.
Throughout a year, in the different months, from
12 to 31 per cent of the beds were found to
contain lice ; the numbers being higher in winter
and lower in summer. Incidentally the result
of his inspection over a number of years was
to reduce these percentages to less than five,
owing to the increased care engendered in the
keepers of the houses. There is no reason why
lice should not lay eggs on blankets, since they
do so on the outer garments to which blankets
correspond during the night. Peacock (1) records
an instance of seeing a nit in this position. Beds
unused for several weeks might therefore harbour
lice, since the hatching of the eggs may be retarded
by cold and the incubation completed later.
Lice also spread by means of garments, and
this is probably the main source of spread in
armies, where clothing is largely communal
property. It has been repeatedly noticed that
when lousy garments are discarded the lice are
liable to congregate outside them and these are
very likely to get on to clean clothing which
comes in contact with them. They have also
been observed to creep out of the necks of kit-
bags and may in this way pass on to clean kits.
The ordinary processes used in a laundry do not
necessarily kill lice and their eggs, since the water
is often not of the lethal temperature and soaking
DISSEMINATION OF BODY-LOUSE 41
in cold, or only warm, soapy water does them
no harm unless the immersion is very prolonged.
Garments reputedly clean from dirt may there-
fore harbour vermin and commence infestation
in one who assumes them.
Lousiness. — If garments containing lice are
worn continually day and night the vermin in-
crease and multiply in a remarkable manner.
Cases are on record where single garments have
held thousands. These are unusual cases and
indicate, in the infested person, either extreme
helplessness or, what is more likely, utter in-
difference to the filthy condition. In attempting
to arrive at an average estimate of lousiness in
troops Peacock (1) excluded these extreme cases.
He found that where 95 per cent of the men had
lice upon them the average number was twenty
lice a man, the range being from ten to thirty.
In another series of men he found about 3 per
cent with more than 350 lice each, while one
shirt he examined was estimated to contain
10,428 lice and 10,253 eggs.
It has been already stated that lice tend to
bite more especially in the regions of the body
against which the clothing presses. When not
feeding they congregate, especially along the
seams and in folds of the clothing. They are
markedly gregarious in their habits, being often
seen in masses and giving rise to the soldier's
term of " lousy lice," that is lice with lice upon
them. They and their eggs may be found on
42 LICE AND THEIR MENACE TO MAN
>.
any garment of the infested person, either inside
or outside, but they are most prevalent inside
the shirt or undershirt, and trousers or drawers.
They are particularly liable to creep into deep
crevices such as the folds of a kilt or the waist-
band of pyjama trousers.
It is important to remember in inspecting
people for lousiness that the eggs of this louse
may be laid on the hair of the body. In this
position they are very difficult to see, but if the
inspection is carried out carefully and in a good
light they will often be revealed. It is practically
impossible to say whether isolated eggs found in
these positions are those of this or the head-louse,
the only difference between them being the very
elusive one of size. The matter has therefore
been the subject of some controversy, as some
observers, perhaps unaware that the head-louse
may infest the body hair, have recorded the nits
of the body-louse in these positions in large
numbers. That body-lice do lay eggs on the
body hair we finally proved in the experiments
described in Chapter VIII., where men were
artificially infested with body-lice for a night.
In one experiment we found a dozen freshly laid
eggs on the pubic hair of one of the men who
was, of course, louse-free before the experiment.
To make quite certain that they had been laid
during this night, the eggs, after they had been
cut off, were incubated and in due course lice
emerged from them.
DISSEMINATION OF BODY-LOUSE 43
Body-lice are found on man all over the world,
and there is probably no tribe free from them.
They are, however, less prevalent in tropical than
in temperate and cold climates, and in temperate
regions are less numerous in summer than in
winter. This is in correlation with the different
habits of people in the winter. Then under-
clothing is more likely to be of wool than of cotton,
and lice prefer the former material. It is also
the custom with many people in this country,
for some reason that is difficult to understand,
to change woollen garments less frequently than
cotton ones. Among certain classes in winter
the day clothing is also worn at night. People
also at this time keep more indoors and crowd
together over stoves. All these habits are in
favour of the spread and increase of lice, and
there is no creature in creation more ready to
seize Time by the forelock.
REFERENCES
(1) PEACOCK, A. 1). " The Louse Problem at the Western Front,"
Journal Royal Army Medical Corps, vol. xxvii. pp. .31 -GO.
(2) 'Seellef. (1), Chap. III.
CHAPTER V
DISINFESTATION
BY disinfestation is meant the freeing of the body
and clothing of lice and their eggs or nits. This
may be done in a variety of ways.
Hand-picking. — The most natural, and inci-
dentally the least effective, method to adopt is
the mechanical one of removing the lice by means
of the fingers. The word " lousing " was used by
old English writers to denote this process, when,
as to-day, lice were so common as to be a matter
of interest to every one, and now that they may
again be mentioned without bating the breath
the somewhat disgusting word has been revived.
This is the method adopted by monkeys, which
may be constantly seen searching in one another's
hair and devouring all the vermin they find.
Primitive peoples often do the same thing, even
to the eating, with apparent pleasure, of the lice
removed. More civilised folks have neither the
time nor the patience to practise this hand-
picking with any thoroughness, and very good
eyesight is required to detect the young lice and
every nit. Moreover, many of the nits and even
DISINFESTATION 45
the lice themselves are so deeply embedded in
seams of the clothing that they cannot be reached
by means of the fingers.
Brushing. — Brushing the clothing with a very
stiff brush has been recommended, especially in
localities where the nights are very cold. In such
places if the clothing is discarded during the night
the lice are torpid in the morning and many can
be removed by means of the brush, but the eggs
are not affected. The operation has therefore to
be carried out daily and over a long period of time,
and precautions have to be taken that the lice
do not fall where they may again have the oppor-
tunity of creeping on to people. These mechanical
means of disinfestation for body-lice are tedious,
unsatisfactory, and not to be recommended if
other methods are available.
Ironing. — An advance on hand-picking is the
method of killing the vermin by means of heat
applied locally to the clothing by means of hot
irons. This has been used to some extent in the
armies in the field. The irons should be heavy
ones and should be as hot as possible without
scorching the clothing. They should be passed
slowly over the whole surface of the garments,
inside and outside, and should linger along the
seams to allow the heat to penetrate. The Ger-
mans have modified this method by providing iron
sheets, heated from inside, against which clothing
may be pressed. It should be obvious that
it is difficult to free of vermin a set of garments
46 LICE AND THEIR MENACE TO MAN
by these means, owing, once more, to those em-
bedded in the seams, which often cannot be
reached by sufficient heat to destroy them without
damaging the fabric thereby. The soldier in the
field will often take off his shirt and pass the
lighted end of a cigarette over the lice and eggs
where they most thickly congregate, killing all
that are touched. This is the method of despair,
but unfortunately in the past has often been the
only one available.
Dry Storage. — Clothing may be freed of lice by
the slow method of storing it in a dry atmosphere
until all are dead. The warmer and drier the air
the more quickly will this be accomplished. As
indicated previously, the eggs of lice will not hatch
if the temperature at which they are kept is
below 72° F. The object of this storing should
be to make the eggs hatch quickly or else dry up
and die. Whatever the temperature the lice will
all be dead at the end of ten days, but if the air
is moist, eggs might still be alive at the end of this
period and lice might emerge from them if the
garments were then worn again. Nuttall(l) ad-
vises that clothing so stored in a dry atmosphere
should be left for at least two to three weeks,
and may then be considered quite safe.
Heat. — The most practical method of freeing
clothing from lice in all stages is by means of heat.
In the Army the idea has become prevalent that
it is a very difficult matter to kill lice by this
mean's. A man may say that he bolted his shirt
DISINFESTATION 47
for half an hour, and after assuming it, it was as
lousy as ever. Others will assert that, after their
clothing had been officially disinfested in the
ovens, in a day or two they were as bad as before.
Such tales, arising from misapprehension, spread
about among the civil population will give them
too an idea of the difficulties of destroying the
pest. The explanation of these statements is
that often in the past disinfestation has not been
thoroughly carried out. At first it was the
custom to treat shirts only, leaving all the other
garments untouched and often very verminous.
Later the importance of treating all the clothing
was realised, but no attention was paid to the
bodies of the men, the hair of which might
harbour both lice and nits, most of which were
undamaged by the bath which always accompanies
the treatment. In the new era of things the
bodies as well as the clothing are beginning to be
cleaned, and great improvement may be expected.
Moreover the heating of the clothing at times may
have been faultily or carelessly done. The cloth-
ing may have been packed so closely in the hot
chamber that though the specified time was
allowed to the load the heat has not had time to
penetrate throughout the mass. Another fault
has often been that it was considered impractic-
able to treat all the men who associated closely
together at one and the same time. Thus
cleansed men might sleep close to one who had
not been treated, with the result of immediate
48 LICE AND THEIR MENACE TO MAN
reinfestation. All this has led often in the past
to disinfestation falling into disrepute among the
men.
Momentary immersion in boiling water of an
individual louse or egg kills it at once. It would
be as impossible for a nit to hatch after this as it
would be for a chicken to emerge from a boiled
hen's egg. Boiling the most verminous garment
for one minute will render it completely harmless,
and there can be no better or safer treatment for
an article the fabric of which would not be
damaged by this drastic process. As, however,
woollen garments shrink under this treatment, it
is necessary for them to use a lower temperature
and to allow a longer time for the penetration of
the heat. An analogous case is the boiling of a
hen's egg. If this is immersed in boiling water for
four or five minutes it becomes " hard-boiled."
If it is placed in water at a temperature of 165° F.
for a sufficiently long time its contents coagulate
equally and it becomes " hard-boiled." In the
first case where much heat is available penetra-
tion is more quickly, attained than in the latter,
where there is less heat available, but the result
in the end is the same. So with lice far lower
temperatures than that of boiling water may be
used to kill them, but an increasing time must be
allowed for the operation the lower the tempera-
ture used.
It makes little difference to the result whether
the heat is dry or wet, that is, whether the opera-
DISINFESTATION 49
tion is carried out in a steamer or an oven, as
far as the lice alone are concerned. When it is
necessary to guard also against the infectivity of
their excreta, which always cling to the fibres
of infested garments, a steaming heat must be
used. The infecting power of the excreta of lice
infected with trench fever is not destroyed by
the dry heat to which garments are usually
exposed. A garment which has been worn by a
lousy person who has trench fever, if freed from
lice by dry heat as ordinarily used, is liable
to cause an attack of the disease in a healthy
man who wears it, as the still virulent excreta
may enter small scratches (see Chapter XI.).
Exposure to wet or dry heat at a temperature of
130° F. (55° C.) for twenty minutes or 140° F.
(60° C.) for fifteen minutes will kill all lice and
nits, provided that the time is calculated from the
moment when penetration of the garment con-
taining them has been completed by the heat.
It should not be calculated from the moment at
which the garments are put into the chambers.
So far as our knowledge at present goes, to destroy
the trench fever virus of the excreta and render
them harmless a steaming atmosphere of a
temperature of 60° C. for twenty minutes is
necessary, and this should be the minimum used.
Knowledge of the time necessary for the thorough
penetration of the garments being treated can
only be gained by experiment with the type of
hot chamber used.
E
50 LICE AND THEIR MENACE TO MAN
A number of perfectly satisfactory disinfectors
for civilian purposes are on sale by various
sanitary engineers, and one or another pattern
is to be found at the municipal cleansing stations
now established in some places. The proper
course for the unfortunate civilian who becomes
lousy is to obtain access to one of these, if avail-
able, and have his garments treated by experienced
hands. In the home it can be done in the baking
oven or in a steamer used for boiling clothes.
In the former case it is unlikely that there can
be any standard of the temperature, and care
would have to be taken that the heat was not
so great as to scorch or burn the garments. The
process would be most safely carried out after
the fire had been withdrawn and the oven was
cooling, when the articles could be left in over-
night. If a boiler or " copper " is used, a wooden
stool may be placed in the water so that the
seat comes just above the surface, and the clothing
may be loosely piled on that. After steam issues
freely round the lid the operation should proceed
for an hour. Moist heat damages leather goods,
and for them dry heat should be used.
As in these operations the heating standard
has not been recorded, the appearance of dead
lice and nits should be known so that it may be
told by inspection whether the vermin on the
treated garments are really destroyed. Lice
under adverse circumstances, such as immersion
in water not sufficiently hot to kill them, have
DISINFESTATION 51
a habit of becoming unconscious, exhibiting no
movement, and the uninitiated may wrongly
assume that they are dead. A louse that has
been killed by dry heat becomes dark-coloured
and brittle, while the egg collapses and turns
brown. When killed by wet heat they both
become opaque and white. If there is any doubt
as to whether the lice are dead or not a few should
be placed in a vessel of glass or china, out of which
they are unable to crawl, and should be placed
in a warm place for a few hours. If alive they
may then be seen moving the legs and trying
to walk. It is a difficult matter for the in-
experienced to decide whether the eggs are killed
or not, and it is advisable to be generous with
both heat and time in the treatment and so
' make assurance double sure."
Cleansing by means of heat is the method most
employed in all the armies. In disinfestation of
the armies in the field there have been many very
real and great difficulties to overcome. One of
these was the failure to recognise how essential to
the well-being of the troops it is that they should
be louse-free, to the benefit of their health as well
as their comfort. The disorganisation which
wholesale disinfestation caused was therefore con-
sidered to be unwarranted. Cleansing stations
were often so far removed from the trenches that
it was actually impracticable to bring the men
to them except when they were resting near a
station. These difficulties are not insurmount-
52 LICE AND THEIR MENACE TO MAN
able and much improvement has taken place.
If the men cannot be taken to the cleansing
stations these should be taken to the men.
Each unit should be supplied with a simple
cleansing apparatus which should be as mobile
as a field kitchen and considered almost as
essential. The hot chambers designed by Captain
Orr of the Canadian Medical Service, and by
Captain Grant and Captain Peacock of the
R.A.M.C., which have been found to give such
satisfactory results, could easily be modified and
put on wheels.
A very simple and portable apparatus which
has been found satisfactory is that known as the
" Stammers' Serbian Barrel," while another
mobile improvisation is the disinfestation train.
Early in 1915, when the British Medical Sanitary
Mission under Colonel William Hunter, C.B.,
A. M.S., was sent to Serbia to assist in controlling
the terrible epidemics of typhus and typhoid fever
which were raging alike in the Serbian Army and
among the civil population, it was found necessary
to employ disinfestation on a vast scale. No
elaborate disinfestors were available, nor the
materials from which such could be constructed.
Out of what material was to hand these two very
effective disinfestors were devised by Lieutenant
Colonel G. F. Stammers, and they have been used
since in stemming with good effect the outbreaks
of relapsing fever in Egypt, which threatened to
assume serious proportions. In both the train
DISINFESTATION 53
and the barrel the effect of current steam is used
to destroy the lice. In the case of the train the
steam is obtained from the engine, which delivers
a generous supply under a pressure of 60-110 Ibs.
The steam is led by pipes into ordinary iron goods
vans, into which it is discharged. The vans are
little modified, being merely provided with shelves
on which the articles under treatment are stacked.
The men whose garments are to be treated bind
them all in a bundle in the blanket, and these are
placed on the shelves "and on the gangway be-
tween the shelves, the steam nozzles being left
unimpeded. The steam is then turned on and
the door closed. The temperature quickly rises
to 105° C., and this penetrates right through the
bundles, as has been shown by means of ther-
mometers placed in the least accessible parts.
The van is not made air-tight, so that little pressure
is caused and the excess of steam escapes under
the door. At the end of an hour the current of
steam is stopped, the door is opened and the kits
removed. Since the moisture which at first con-
densed in the clothing has again become converted
into steam, a shake in the open air is all that is
necessary to dry the garments, and within two
hours of their arrival at the train the men are
able to leave with a louse-free outfit. It may be
remarked in parenthesis that during this period
their bodies should have received attention. A
busy fortnight for such a van disinfestor is thus
described by Colonel Hunter. " A most striking
54 LICE AND THEIR MENACE TO MAN
illustration of this mobility was afforded in one
instance, where a van disinfector, which had just
disinfected a division of 18,000 troops in twelve
days in one area, went off about 500 miles to a
centre in Southern Egypt, where some cases of
FIG. 10. — THE "STAMMERS" OR SERBIAN BARREL.
An improvised disinfestor. (After Hunter.)
«, heavy stone ; 6, escaping steam ; c, wooden grid ; d, sand-bag
collar to conserve steam.
typhus had occurred among the native labourers.
It disinfected the whole of the troops and labourers
(1500 in number) in three days, and was back at
work again in its former area disinfecting another
division on the fourth day " (2).
The barrel disinfestor was devised three days
DISINFESTATION 55
after the arrival of the Mission at Nish, and the
following week was destroying lice wholesale. It
has this great advantage that any small body of
men may have a private disinfestor always with
them at a very small cost. It consists of an
ordinary large wine barrel (Fig. 10), in the bottom
of which a number of holes are bored. This is
placed over an open boiler (an empty paraffin
drum will suffice) in such a manner that the
steam can pass freely through the openings into
the barrel. A circular sand-bag piping is placed
between the boiler and the barrel to prevent the
waste of steam. A little distance above the
perforated baSe a wooden grid is constructed, and
on this the articles to be treated are placed.
The whole is then closed by means of a heavy
wooden lid which is weighted down with stones.
A barrel of a capacity of sixty gallons will deal
with four complete kits or seven blankets at a
time. After the steam escaping round the lid is
too hot to be borne by the hand an hour is allowed
for the thorough treatment of the load.
Ordinary galvanised iron sanitary bins (Fig. 11)
were also used in Serbia. A foot of water with
an iron grid over it is placed in the bin and the
whole over a fire. It is then worked in precisely
the same manner as the Stammers' barrel.
The steam disinfestation chamber which was
first used in the Canadian Medical Service con-
sists of a chamber with an inner lining of sheet
asbestos and an outer layer of corrugated iron
56 LICE AND THEIR MENACE TO MAN
or brick, there being a space of two inches be-
tween the lining and the outer wall in order to
conserve the heat. By the side of the chamber
is a vertical boiler which supplies the steam.
The whole structure is built on a concrete floor.
From the boiler runs a system of radiator pipes,
OlotWs
-T — f — T — 1-
FIG. 11. — IMPROVISED DISINFESTOR.
An ordinary galvanised iron sanitary bin. (After Hunter.)
a, escaping steam ; b, wire grid.
which pass along the sides and roof of the chamber,
and a second series run along the floor. From the
latter system live steam is allowed to enter by
a number of jets. The water condensed flows
away by means of a drain in the concrete base.
There is a wooden grid raised a little above the
floor to allow the operators to move about in
DISINFESTATION 57
comfort when they load and unload. The
material treated is hung loosely on a number of
pegs, the garments being turned inside out. In
the routine working this chamber is kept con-
stantly hot by means of the radiator pipes.
When the operation commences the doors are
closed and steam under pressure is allowed to
enter through the jets in the floor system of pipes,
and the lethal temperature for the lice is quickly
attained in all parts of the chamber, the time
necessary for this varying with such factors as
the size of the chamber, the quality and amount
of the load, the size of the boiler, and the steam
pressure. This heat is maintained for as long as
is necessary, the higher the temperature attained
the shorter the period required. A check is kept
on this by means of a maximum thermometer,
which is wrapped in several thicknesses of blanket
and placed in that position which experience
shows is the coolest. For the exact working of
the machine so as to avoid the waste of fuel
caused by supplying more heat than is necessary,
a knowledge of the particular type in use must
be gained by a series of experiments. At the
end of the operation the steam is shut off at the
jets, the door is slightly opened, as is also the
outlet of the drainage system in the floor, and
the dry heat supplied by the radiator system
is allowed to act for a few minutes to partially
dry the contents.
Although disinfestation by wet heat must, for
58 LICE AND THEIR MENACE TO MAN
reasons given above, be considered the ideal
method, among the armies in the field it is not
found practicable to use it for the treatment of
garments in the winter in Europe, owing to the
difficulty of drying them. For this reason hot-
air chambers are mainly used now, and an effort
is made to raise the temperature in them as high
as may be done with safety. One of these is of
the form known as the "Russian pit," in which
the chamber consists of a large hole dug in the
ground in which braziers are placed, the roof
being heavily earthed up. Another type con-
sists of a chamber of corrugated iron with a
double wall and roof which is built over a pit.
The braziers are placed in the pit and the hot
air passes through holes in the floor up into the
chamber.
The thermometers placed in the chambers
record only the highest temperature attained,
and not the length of time that the lethal heat
has been maintained. Instruments which would
do this are too costly and delicate to issue for
routine work. There is scope for the ingenious
here to invent some simple instrument which
would record the necessary data. Bacot has
suggested that a piece of paraffin wax of known
melting-point and of such a size that it would
just entirely melt in the requisite time should be
used. Thus if the machine should maintain a
temperature of 60° C. for twenty minutes the
melting-point of the wax would be 60° C. and a
DISINFESTATION 59
piece which would just melt entirely in twenty
minutes at this temperature would be used, being
put into the coolest part of the chamber. If,
when the chamber was opened, this was seen to
have entirely melted it would be known that the
load had been safely treated. If a piece remained
floating in the melted wax it would be obvious
that there was some flaw in the working of the
machine. The same piece of wax, kept in a
vessel, could be used time after time.
An ideal disinfestor for army purposes has
yet to be invented. Its requisites are : that it
should be rapid in operation, attaining the
necessary temperature quickly ; it should be
easy to load and unload ; it should be inexpensive
in initial cost and in operation ; it should be
portable. With many patterns there is much
time lost in loading and unloading, since the
chamber must cool to some extent for the operators
to enter, and thus heat is lost. Some of this time
would be saved if each chamber was fitted with
an extra wooden rack for the clothing, which
could be loaded while the machine was operating
on the other, and when the latter was finished it
could be withdrawn for unloading and the other
thrust into its place. An oven of this type would
operate nearly twice as quickly as one with a
single rack. Such an idea is incorporated in one
of the chambers most used in France. In any
type the hot air or steam should circulate and
not be stationary, as by this means an even
60 LICE AND THEIR MENACE TO MAN
temperature throughout the mass of clothing is
more quickly attained.
Treatment by Chemicals and Greases.—
Chemicals may be used in relation to lice in two
ways : to destroy the lice and nits on clothing
and hair, or to repel them and prevent them from
establishing themselves. The latter expedient
would of course never be used by the person
going about in ordinary civil life, as all are dis-
agreeable, but may be found of use to those, such
as sanitary inspectors and district nurses, who
are particularly liable owing to their vocations
to come in contact with lousy people. For the
poisoning of lice the type of substance most
commonly used is either an oil or a grease, with
or without some other active ingredient. Any
greasy substance which kills lice may be regarded
in a way as a repellant, in that it would destroy
any louse which obtained access before it could
establish a colony, though it might be able to feed
first. Strongly smelling oils such as eucalyptus,
certain coal-tar products such as naphthalene
and carbolic acid, and some creosoty wood oils
such as birch tar oil, are all to some extent repel-
lant in their action on lice. As Bacot (3) showed,
they exert only an effect over quite a small radius,
and for this reason the wearing of a belt impreg-
nated with such substances, or one or more small
bags of them slung in different positions about
the body, cannot be expected to be of much use,
as their action would be only local and lice could
DISINFESTATION 61
live and thrive within a few inches of them. It
is therefore imperative in using repellant sub-
stances to either smear the body over with them
or to impregnate the clothing. Several are suit-
able for this. The naphthalene paste described
below may be smeared over the inside of the
underclothing, especially along the seams. N.C.I.
powder as used in the Army has also a repellant
action on lice. One or other of these substances
should undoubtedly be used generously by any
one whose duty it is to work amongst the sick
in any louse-borne epidemic, even if louse-proof
overalls are worn. In their absence any grease
is an advantage, even rancid butter being used
by some people.
Very many substances have been recommended
from time to time for the destruction of lice on
clothing and the body, and a few of these will be
mentioned here.
Lysol is- a well-known standard disinfectant
which may be purchased from any chemist or
prepared by heating together for half an hour
equal parts of crude carbolic acid and soft soap.
This is used in a 2 per cent solution (1 table-
spoonful in 2 1 pints of water) for the destruction
of lice. At all ordinary temperatures this kills
nits in half an hour if the garments containing
them are steeped in the solution. The lice, how-
ever, survive if the temperature of the fluid is
below blood heat, and it should therefore for
safety have a temperature of about 104° F.
62 LICE AND THEIR MENACE TO MAN
(40° C.) ; that is, it should be distinctly hot to
the hand, to make certain of the complete destruc-
tion of the pest. If it is cooler than this, some
of the lice are liable " to come to life " again even
after the elapse of twelve hours. The advantages
of this treatment by solution instead of by heat
are that the necessary standard is more easily
attained in ordinary household use, and it may
be safely employed for articles which would be
damaged by great heat, such as woollen garments,
feathers, brushes, etc. For wholesale disinfest-
ation it cannot be said to compare with heat
in convenience. Lice killed by this means turn
black quickly, while the nits turn brown and
shrivel up.
Paraffin (kerosene) and petrol destroy lice and
the nits. They are somewhat dangerous in use
owing to their inflammability, and petrol is, of
course, prohibitive at present. They are for
various reasons less satisfactory for the treatment
of garments than lysol solution. Clothing should
be steeped in them for half an hour to make
certain of the destruction of all the vermin.
Naphthalene and soft soap was recommended
by Bacot and Copeman, and is used in the Army.
The unrefined form of the naphthalene is most
effective and is known as " crude un whizzed
naphthalene." Four parts of this are mixed
with one part of soft soap, resulting in an un-
pleasant dirty ointment which is very efficacious.
It should be rubbed on the inside of underclothing
DISINFESTATION 63
and the effect will last several days. It will be
found to be equally useful for the head- and
crab-louse. It should not, however, be made to
supersede treatment by heat. It is an additional
remedy and not an alternative one when heat
is available.
N.C.I, is a powder composed of crushed
naphthalene with 2 per cent creosote and 2 per
cent iodoform. It has been used in the Army,
and Peacock (4), who carefully investigated its
effect, spoke very favourably of it. It should be
dusted inside the underclothing, and its killing
and deterrent action lasts for several days. It
causes a little irritation where the skin is moist.
Vermijelli is a proprietary name for a refined
form of a remedy recommended by Professor
Maxwell Lefroy, who states that the formula is
crude mineral oil 5| pints, soft soap 3 Ibs., water
about | a pint. This is rubbed all over the body
and inside the underclothing. Its action is prob-
ably the same as that of any other grease, namely
that it runs into the breathing holes of the
insects and smothers them. It is less unpleasant
in use than most remedies.
Sulphur has an entirely false reputation as a
louse-destroyer. It is used by people in the
East End of London and amongst hop-pickers,
who carry a lump of it in the pocket as a talis-
man against the pest. A person can, however,
eat sulphur, as we have proved, until the odour
from the skin is perceptible at a distance of a
64 LICE AND THEIR MENACE TO MAN
couple of feet and until his health begins to
suffer, and yet lice fed upon him thrive. It may
be considered useless.
Mercury in the form of various ointments has
been much used, especially the blue mercurial
ointment for crab-lice. It is certainly efficacious,
but is rather dangerous to use owing to its absorp-
tion by the skin. The naphthalene ointment
mentioned above will be found equally effective
and perfectly safe.
General Remarks on Disinfestation. — The great
principle in all disinfestation is to be thorough.
All articles of clothing and bedding which have
come in contact with a lousy person should be
treated with either heat or solution as described
above. The reinfestation of these should be
avoided, and care should be taken that they are
not laid after cleansing in the spot where they
were before the treatment. While these are being
treated the body should receive careful attention
at the same time. It should be remembered
that though a hot bath may alleviate lousiness
it is not a cure for it. If a person is liable through
his occupation to repeated infestation, as in the
case of the armies, it is advisable to remove the
body hair. The inconvenience resulting from
this has been exaggerated. In this process care
should be taken not to lacerate the skin as the
trench-fever virus may enter through the cuts.
This did indeed happen amongst a body of men
in the German army.
DISINFESTATION 65
Where several people in the same house, or
in a class of a school, or an army unit, require
disinfestation, the whole process should, as far
as possible, be carried out at one and the same
time, or the uncleansed may reinfest the cleansed.
Every effort should be made to persuade the
infested to report their condition to the proper
authorities. Soldiers in the field or in training
should be instructed to inspect themselves. The
author has seen men in hospital with the pubic
and axillary hair swarming with lice, and their
invariable remark is that they knew nothing of
it, and this was the case, as their real disgust at
the revelation revealed. The merest glance at
themselves, however, would have shown them
their condition. Ignorance of their own state
is a poor excuse.
Lastly, it cannot be too strongly urged that
the louse problem in civilian life is not the same
as in the armies, though the remedies are the same.
It is simpler, in that cleanliness is more easily
attained ; that contact of people is less close ;
that disinfestation disorganises nothing of any
importance and need not be hurried. It is more
difficult, in that there is less control over the
individual, and the unclean pestiferous person,
if he can avoid institutions, may spread his vermin
far and wide. For these reasons it is better not to
pay too much attention to the tales of the return-
ing soldier about the impossibility of getting rid
of lice. The problem in the armies is hedged
F
66 LICE AND THEIR MENACE TO MAN
round with many real difficulties which the
authorities are endeavouring to overcome. In
civilian life any individual can rid himself of
the heaviest infestation in a few hours, and there
are many institutions, such as public cleansing
stations (though there should be many more),
which are provided to give him any help he may
need.
Prophylaxis against Louse - borne Disease.—
Modern scientists tend more and more to study
the prevention of disease rather than its cure.
It is difficult, often impossible, to eradicate the
germs of a disease from the human body, since
the necessary drugs frequently do more harm to
the tissues than to the invading organisms. The
treatments by means of vaccines and sera are
available for only a relatively few diseases, and
for many will perhaps never be available. How
much better is it, therefore, to endeavour to
prevent the initial entry of the organisms into
the system than to attempt to eradicate them
afterwards. The essence of the prevention of
insect-borne diseases is to get rid of the insects
which convey them from man to man.
We know that if a man is never bitten by a
mosquito he cannot contract malaria ; that if
he does not allow a tsetse-fly to feed upon him
he is safe from sleeping sickness ; that if he can
avoid rat-fleas he will never fall a victim to
bubonic plague. We also know that it is a
council of perfection to advise a man to avoid
DISINFESTATION 67
these things who lives in a country where they
abound. Be he never so careful, sooner or later
he does get bitten by one of the insects, and if
the one that bites happens to be infected with
the disease he is liable to contract it. Sanitarians
are endeavouring to find one means or another
of destroying these insects, and in places with
marked success. For example, the work on the
Panama Canal was impeded and finally stopped
by the two mosquito-borne diseases, malaria and
yellow fever, until methods were adopted for
preventing the breeding of mosquitoes, with con-
sequent reduction in the incidence of the maladies.
The work was then resumed and successfully
completed.
The control of mosquitoes is a very difficult
matter, involving vast schemes of drainage, and
treatment of water that cannot be drained.
The complete disappearance of this pest is never
to be looked for. The preventive methods must
be continued always, or the locality freed from
them will become quickly invaded again by the
immigration of others from neighbouring locali-
ties. The prophylaxis against the sleeping sick-
ness of Africa is even more difficult, since the
country involved swarms with large animals on
which the tsetse-flies live, and the peculiar breed-
ing habits of the flies make them most difficult
insects to attack. In this case it has been found
necessary to depopulate the areas where sleeping
sickness most prevails, pending some more satis-
68 LICE AND THEIR MENACE TO MAN
factory solution to the problem. Bubonic plague,
too, is a most difficult matter, and its solution
lies in the complete destruction of rats as a means
of getting rid of the great reservoir of infection
from which the fleas carry the disease to man.
Compared with these, prophylaxis against louse-
borne disease is a simple problem, and the pros-
pects of eradicating them from the world are
bright compared with those of any other insect-
borne disease. In any organised community
where the will exists in the administration, lice
can be completely exterminated with comparative
ease, and their reintroduction may be guarded
against by the examination of immigrants.
REFERENCES
(1) NUTTALL, G. H. F. " Combating Lousiness among Soldiers and
Civilians/' Parasitology , vol. x. pp. 411-576.
(2) British Medical Journal, August 24, 1918, p. 198— "New Methods
of Disinfection for the Prevention and Arrest of Lice-borne
Diseases," by Colonel W. Hunter, C.B., A. M.S.
(3) BACOT, A. " The Use of Insecticides against Lice," British Medical
Journal, Sept. 30, 1916.
(4) SeeRef. (1), Chap. IV.
CHAPTER VI
THE HEAD-LOUSE (PEDICULUS CAP1T1S)
THE head-louse is the commonest of the three
lice of man in the more cultured countries. It
is rather smaller and more slender than the
body-louse, with slightly deeper constrictions at
the sides of the abdomen, but is otherwise so
much like it that it is very difficult to say whether
an isolated specimen is one or the other. The
distinction between them is rather one of habit
than of structure, and entomologists are begin-
ning to regard the two as biological races of one
species rather than as distinct species. Probably
primitive man, who was much more hairy than
his modern descendants, was infested by a louse
more resembling the head-louse of to-day than
the other, and this was the ancestor of the two
races, which split off from one another at some
time after the adoption of skins as clothing.
Evidence of this is that the claws and gonopods
are specially adapted for dealing with hair, not
cloth. These two forms of lice will, as Bacot(l)
showed, interbreed readily, the males of one
variety crossing with the females of the other,
70 LICE AND THEIR MENACE TO MAN
and vice versa. This is evidence of their close
relationship.
The curious scientist is able to distinguish
between them by breeding them in pill -boxes
under control, and for the rest it is sufficient to
know their distribution on man and to name
them one or the other according to their obvious
habits. If the lice are found on the garments,
and not, or only a few, on the body hair, they are
body-lice. If they are in the hair of the head
or in that of the body, with none, or very few, on
the clothing, they are head-lice. Any on the
body hair should, of course, be first distinguished
from crab-lice, and this is easily done by the
shape. Thirdly, if the lice are numerous on both
the clothing and the hair, an infestation by
both races is indicated. As with the lice, so with
the eggs : if these are few on the body hair and
numerous on the clothing they are probably
those of the body -louse. If they are numerous
on the body hair they are almost certainly those
of the head-louse. Nuttall (2) showed that under
artificial conditions, if both hair and cloth are
available, the head-louse relatively infrequently
lays on the cloth, while the body-louse seems to
have little preference for one or the other.
Under normal conditions, far and away the
most common site in which the head-louse is
found is the head. Children are the most fre-
quent sufferers, and, after these, old people.
These are the two classes of the community who
THE HEAD-LOUSE 71
are most careless in the care of the person.
Females are more often infested than males, as
the hair is longer, affording better concealment
for the lice. While the insects may be found all
over the head, the parts most frequented are the
sides, over the ears, and back, rather than on the
crown. The eggs are laid attached to the hair
close to the scalp, but as the hair on which they
are situated grows they become more distant
from it, and hatched nits may be found quite
a long way from the base of the hairs. It is
possible that the eggs may occasionally be laid
in hats, attached to the cloth of the lining. In
correlation with the smaller size of the parent the
eggs of the head-louse are somewhat less than
those of the body-louse, and the fecundity is
not so great. Otherwise there is little difference
between the two races in their life-history and
their responses to environment.
The spread of head-lice is by methods similar
to those which obtain in body-lice. A person
may become infested by stray lice ; by coming
in contact with a lousy person ; by using the
brushes or head-gear used by one who harbours
the lice ; by having had his hat in contact with
one containing lice. The cloak-room system of
our council schools, where hats are hung on pegs
in close proximity, and often several on one peg,
lends itself to the dissemination of this insect.
The presence of the first intruder is more
likelv to be noticed than in the case of the body-
72 LICE AND THEIR MENACE TO MAN
louse, since the scalp is very sensitive to any
movement in the hair and a lot of scratching
usually accompanies a head infestation. Some
primitive tribes who have elaborately arranged
hair often use special instruments for scratching
the part which itches. The males of the Masha-
kalumbwe people of Northern Rhodesia work
their hair into a kind of cone on the top of the
head. This is prolonged into a stiff upstanding
string of perhaps three feet in length, and ending
in a brightly coloured feather, so that they can
locate one another when hunting on the long-
grassed plains on which they live. Once built up
this head-dress is never taken down again day
or night, and a skewer is used to alleviate itching.
Many other African tribes carry wooden fork-
like combs in their woolly hair, and may often
be seen to remove them, use them for scratching,
and replace them again.
The best precaution against head-lice is the
keeping of the hair cropped very close to the
head. It is undoubtedly on account of this
manner of wearing the hair short that armies are
to-day so little troubled by lice on the head.
School children, boys and girls, should be treated
in the same way until they reach that age when
real cleanliness appeals to them. It is better
to dispense with the attractiveness of long hair
than to risk the health of the child being seriously
damaged, not necessarily by one of the three
epidemic diseases discussed in these pages, but
THE HEAD-LOUSE 73
by scalp troubles, such as eczema, so often started
by the effects of vermin. A second precaution
that is useful is the use of pomades and oils for
the hair. All lice hate grease, which runs over
their bodies and chokes them. It is not necessary
that any medicament should be added to the
grease, and some of the so-called louse-destroying
pomades are poisonous and dangerous in use.
Many primitive tribes have a habit of greasing
heavily both their heads and bodies when fat
or oil is available. In Africa, in most native
gardens quantities of the castor-oil plant may be
seen growing, and apparently the oil produced
is used for no other purpose. The author has
also seen them, when a hippopotamus has been
killed, cut lumps of fat out of the animal and
smear themselves from head to foot. Whether
these precautions owe their origin to their bene-
ficial results in regard to lice, it is hard to say,
but at any rate the benefit accruing to them in
this respect is very real.
Mechanical means are more effective for head-
lice confined to the head than for the body-lice ;
but even with these patience is necessary, and it
can hardly be expected that an established
colony of them can be all removed by the comb
at a single operation, as there is a limit to the
patience of the sufferer if not to that of the
operator. The comb used should have fine
teeth, and a little while before the combing the
hair and scalp should be thoroughly washed
74 LICE AND THEIR MENACE TO MAN
with vinegar, which loosens the nits though it
does not kill them. It has also been recom-
mended by Hewlett that the comb should be
kept hot by repeated dippings in hot water,
since head - lice, like body - lice, are irritated
by heat above that of the body temperature,
and the hot comb approaching makes them
become active, so that they are more easily
caught. The head should be held well over a
sheet of paper, or better, a large dish, and all that
is combed out should be emptied into a fire,
Combing should proceed from the outer edge oJ
the hair to the crown, and the instrument shoulc
press close against the scalp In each stroke
The successive strokes should not be made
haphazard, but should pass gradually round tlu
head, so that each hair from base to tip passes
between the teeth of the comb. Where th(
skin is so much affected that sores have developed
thorough combing is too painful, and gentlei
means should be employed to get rid of the
vermin. Under these circumstances the firsl
and foremost thing to do is to cut the hair verj
short, burning all that is removed. A few pro
tracted washings with a hot solution of 2 per cen
lysol (see p. 61) will then destroy any vermii
left, and though this is painful it will do gooc
rather than harm. In using hot lysol solutioi
it is better to have the patient lying on the back
with the bowl of fluid below the head, and t(
sponge upwards. The irritation is then less
THE HEAD-LOUSE 75
Lysol is a very penetrating substance, and the
fluid is likely to penetrate through the eyelids
if it runs into this region.
An old remedy for head-lice is paraffin oil,
and this is quite effective and safe, provided
precautions are taken to avoid near contact
with flame or fire. The hair should be thoroughly
wetted with the oil, and then wrapped in a towel
arranged turban-wise, or covered by a bathing-
cap. After half an hour it should be well washed
in warm soap and water, and afterwards combed
free of dead lice and nits. As before, this is more
readily done if vinegar is also used. This method,
if properly carried out, is much more certain
than combing alone, any vermin that may escape
the comb having been killed, and so mattering
little. The naphthalene paste, described in the
last chapter, will also be found effective for head-
lice if rubbed well into the scalp and hair. The
best treatment for head-lice on the body hair is
to shave off entirely that infested.
Lastly, in the treatment of this pest, all the
head-gear which may have been worn during
the infestation should be treated by one of the
methods described for clothing in the last chapter,
and should not be again assumed after the head
has been cleansed until this has been done. The
difficulty of getting rid of vermin in the head is
often probably due to this precaution not being
taken.
REFERENCES
(1) See Ref. (3), Chap. III. (2) See Ref. (1), Chap. III.
CHAPTER VII
THE CRAB-LOUSE (PHTHIRUS PUBIS)
THIS abominable insect (Fig. 12) is very readily
distinguished from the two previously discussed,
FIG. 12. — THE CRAB-LOUSE (PHTHIRUS PUBIS). Adult male, (x 45.)
both by its shape and its habits. It is smaller
THE CRAB-LOUSE 77
than either of them, speaking of course of the
adults of each, its body being only about one-
fifteenth of an inch in length and one-thirtieth in
breadth, and while the body-louse is about three
times as long as broad, the crab-louse in length
measures rather less than twice its breadth.
Moreover, while the legs of the body-louse are
well separated and obviously adapted for balan-
FIG. 13. — CLAW OF THIRD LEG OF CRAB-LOUSE GRASPING PUBIC HAIR.
cing the body in locomotion, those of this species
stick straight out, near together, awkwardly from
the body. The first pair of legs are slender, while
the other two pairs are correspondingly stout,
with very strong claws (Fig. 13), most remarkably
adapted for clinging on to hair. The inner edges
of the claws are strongly serrated, much more so
than in the case of the other human lice, and thus
they obtain a firmer hold upon the hair as the
78 LICE AND THEIR MENACE TO MAN
roughened surfaces of pliers strengthen so greatly
their grip on a piece of wire. They are, in fact,
the sloths of the insect world ; for just as the legs
of these animals have become so adapted for
moving from branch to branch in the thick South
American forests that they are helpless on the
ground, so the crab-louse has become even more
modified for its progression in a forest of hair and
cannot progress on any other medium. It is
~ indeed one of the most specialised of parasitic
insects. To continue the comparison of this with
the body-louse, its head is larger in proportion to
its body, and there is less distinction between the
thorax and the abdomen, there being no " waist "
at all. There are three protuberances on each
side of the abdomen, two pairs of which bear long
hairs, and the insect is altogether more hairy-
looking than the body-louse. Often these lice
are so thickly encrusted with the dried salts of
sweat, which quite obscure them, that they look
more like small masses of dirt than insects.
Until very recently indeed little was known
about the habits of the crab-louse beyond a few
very obvious facts as to the parts they frequent
and where their eggs are laid. They cannot be
reared in boxes covered with chiffon, as are the
other two species, for laboratory work ; but Pro-
fessor Nuttall (1) has recently shown that it is
possible to rear them by confining them to the
hairs of the leg on a space enclosed by a silk
stocking with an elastic garter above and below
THE CRAB-LOUSE 79
them. As a result of his studies he has taught
us much about the pest.
Just as the head-louse is usually confined to
the head but may establish itself on other parts,
so the crab-louse usually frequents the hair of the
pubis and peri-anal region, but may be found also,
or alternatively, in the armpits, where it is fairly
common ; on the scattered hair of the trunk and
limbs ; on the beard and moustache ; on the
eyebrows and eyelashes ; and on the scalp hair.
The preceding positions are mentioned in the
order of frequency with which the lice are found
upon them. On the hair of the head it is very
rare indeed, probably because this has such very
different qualities from the body hair, such as
abundance and calibre.
The eggs (Fig. 6) are laid cemented on to the
hairs in a manner similar to those of the other
species ; but from these they may be distinguished
easily, by means of a lens of low power, by their
slightly smaller size, their darker colour, and the
character of the cap or operculum, which in this
species is more conical and symmetrically sculp-
tured by prominent round nodules which cover
its whole surface. The cement also covers a
larger length of the hair, running considerably
below the base of the egg. The eggs hatch in
from six to eight days. The newly emerged louse
moves at once to the base of the hair on which it
was hatched out, and, clinging to this hair alone,
buries its mouth parts in the skin and begins to
80 LICE AND THEIR MENACE TO MAN
feed. It does not withdraw its mouth parts, but
continues in this one position for about five days,
sucking blood intermittently, and keeping itself
continually gorged, while it defaecates in a dis-
gusting manner. It moults three times, and after
the first moult it moves occasionally for a short
distance, but continues to take very protracted
and generous meals. It now holds two hairs
instead of one, and hangs with its body suspended
between them. In moving it always retains a
hair in the grasp of the legs of one side until it
has established its grip on another by means of
those of the other side. This sidling movement,
and the ungainly shape of the creature, earned
it its popular name. The growth of this louse
occupies a little over a fortnight, and the adult
female lays an average of about two eggs a day
for about another fortnight, by which time it
appears to have completed its natural span of life.
The insect has therefore a lower fecundity than
the others, but its eggs are nearly twice as large
in proportion to the size of its body.
An idea is very prevalent that the young crab-
louse burrows under the skin. This is not the
case ; the false impression is gained by its very
close adherence to the surface and the difficulty
of dislodging it with the fingers.
The spread of the crab-louse is usually by its
passage in some form from one sex to the other
during coitus, but it may be picked up by other
means. It was thought that it was disseminated
THE CRAB-LOUSE 81
by the migration of the lice themselves, and this
doubtless does take place; but Nuttall(l) thinks
that spread is mainly by means of the egg which
becomes detached with the hair to which it is
cemented. The hairs of the body are continually
being shed and are particularly dislodged by
scratching. The dislodgment is not a sudden
process unless the hair is pulled out by force, as,
when loosened, it remains at first entangled in
the other hair and works free by a gradual pro-
cess. In its youngest stage the louse holds a
single hair, but it feeds continually so that if the
hair to which it had attached itself came loose it
would, if time were allowed, transfer itself to
another, the base of which was still in the skin.
In the older stages it holds two adjacent hairs,
and if one worked loose it would grasp another
so that it could keep its mouth against the skin
surface. The louse is not therefore very likely
to become dislodged with the loose hairs. The
egg, however, remains attached to its single hair
whether this is drawn out with force or becomes
detached and works free slowly. The hairs are
particularly liable to be shed about latrines, since
the sudden change of temperature causes the
irritation of the bites to increase and it is also an
opportune moment for scratching. The crinkled
shape of the hair makes it very likely to become
entangled in other hair or in the clothing of others
than the infested person. The lice may also be
spread by means of the clothing of the infested
G
82 LICE AND THEIR MENACE TO MAN
if the garments are assumed by others, unless
they have been treated first. After a person has
been freed from the lice and the eggs have all
been killed, he is liable to reinfest himself if he
wears again the clothing untreated which he
wore during the attack, since hairs with eggs on
them may have been dislodged and remain in the
fabric of the garments.
The most effective method of disinfestation is
to shave off all the hair from the parts affected,
at the same time applying some louse-destroying
ointment as an additional precaution. At the
same time all underclothing worn during the
attack should be treated by either heat or hot
2 per cent lysol solution as described for body-
lice. Blue mercurial ointment was a very
favoured remedy for these lice, but it is not
necessary to use so dangerous a substance since
the naphthalene paste (p. 62) will be found as
effective. It should not be applied to eyelashes ;
lice and nits in this position should be pulled off
with forceps.
Crab-lice have not been shown to convey
disease, but this does not necessarily mean that
they cannot do so. So far as the author is aware,
no experimental work has yet been done with
these insects on this line, probably owing to the
difficulty of breeding them for experimental
purposes. It is possible that they may be able
to convey any or all of the diseases carried by
body-lice. However, if the excellent case which
THE CRAB-LOUSE 83
Nuttall(l) makes out of the mode of spread of
the pest be correct, it could play little part in the
development of epidemics. By analogy, young
hatching from the eggs should be unable to cause
typhus or trench fever, though if the parent were
infected with relapsing fever the offspring might
be able to convey that complaint (see p. 106).
It is recorded that when numerous these lice
may cause a simple fever which disappears when
the parasites are removed. It is therefore pre-
sumably caused by the action of the salivary
juice injected and not by any organism. The
bites often cause no itching at all, so that a person
may be heavily infested and know nothing of it.
In other cases the itching may be very severe,
the variation being according to the individual
peculiarities of the infested. A curious effect of
the bite is that frequently blue patches appear
on the skin at the spots where the insect has been
feeding (2).
REFERENCES
(1) NUTTALL, G. H. F. " The Biology of Phthirus pubis," Parasito-
logy, vol. x. pp. 383-405.
(2) NUTTALL, G. H. F. " The Pathological Effects of Phthirus pubis"
Parasitoloyy, vol. x. pp. 375-382.
CHAPTER VIII
THE INCREASED MIGRATION OF BODY-LICE
IN FEVERS
SOME experiments to study the migration of
body-lice from one person to another under
certain conditions were carried out by Major W.
Byam, R.A.M.C., and the author at the New
End Military Hospital, Hampstead, in connec-
tion with the investigations into the etiology of
trench fever. As the results of these experi-
ments have not previously been published they
are given in detail here.
Several writers have drawn attention to the
unusual activity of lice when exposed to tempera-
tures higher than those to which they are ordi-
narily accustomed. We observed that when lice
in the glass - bottomed pill - boxes covered by
chiffon were being fed on a man in a fever they
did not remain on the chiffon against the skin,
as they usually do after they have fed, but
migrated into the upper parts of the boxes against
the glass, as far away from the heat as they could
get. What would be the behaviour of the lice
MIGRATION OF BODY-LICE 85
free on the body of a man who develops the
fever of one of the louse-borne diseases appeared
at once to be a most important question. These
lice have obtained the infecting feed of blood
either before the temperature has commenced to
rise or as it rises. If the rising temperature then
caused them to scatter, the spread of the disease
would be increasingly accelerated.
Some of the soldiers under treatment at the
hospital and the civilians who were allowing us
to infect them with trench fever offered them-
selves for these exceedingly unpleasant experi-
ments, being willing to spend highly uncomfort-
able nights in the interests of science. The
experiments were carried out in a small room
with distempered walls and boarded floor. It
was not artificially heated, and the work was
done in February, when it was cold and raw.
A bed was made up on the floor of the room con-
sisting of two mattresses placed side by side and
covered by a white blanket, with ordinary pillows
and pillow-slips, and four white blankets to
cover the men. Into this bed the men, clad in
flannelette pyjamas, went in pairs, and two
hundred body-lice were released on the abdomen
of one of them in the region of the umbilicus.
The lice used were in each case adults and well-
grown nymphs, since young larvae might have
proved difficult to retrieve. The men were in-
structed not to get out of bed ; not to touch the
insects ; to avoid scratching if possible ; to inter-
86 LICE AND THEIR MENACE TO MAN
fere in no way with their roaming. They were
also asked to note when and where they were
bitten. At the end of each experiment all the
bedding was passed through a disinfestor.
Every two hours the temperatures of both
men were taken and notes were made as to the
condition of their skins, whether moist or dry.
Sometimes a brief observation was made on the
scattering of the lice at the time of the visits,
and the men were questioned as to the biting.
The experiments were allowed to proceed for
varying periods, generally about sixteen hours,
and the lice were then again collected and their
distribution on the men and blankets noted under
the following headings : (1) outside of top
blanket; (2) top, or third, blanket interspace;
(3) second blanket interspace ; (4) first blanket
interspace ; (5) blanket above men, under side,
those above each man being recorded separately ;
(6) blanket below men, upper side, the lice below
each man being recorded separately ; (7) pillows
of each ; (8) mattresses, also for each man ; (9)
outside pyjama jacket of each ; (10) inside pyjama
jacket of each; (11) outside pyjama trousers of
each; (12) inside pyjama trousers of each; (13)
on the person ; and (14) the missing lice which
presumably had wandered right away from the
bed and had probably crept into the cracks
between the boards of the floors. It was found
necessary in each case to rip along the tape holes
of the pyjama trousers and to open any seams
MIGRATION OF BODY-LICE 87
into which they might have obtained access.
In this way complete data of the migrations of
the lice were obtained. Six of these experiments
were carried out, in three of which the man upon
whom the lice were released, called the primary
host, was febrile, and in three he was normal.
His bed-fellow, the secondary host, was normal
in each case. The febrile men were in each case
suffering from trench fever.
The details of these experiments are given
below. The exact distribution of the lice is not
included, to avoid laborious detail. The numbers
of the lice in the various positions are given in
percentages of the numbers recovered. Those
marked "on or about " the host are the ones
which were on the body, inside and outside the
pyjamas, and on the inner side of the blankets
immediately against the men. These also in-
clude the small numbers which were on the pillows
and between the upper blankets. The lice were
assigned to the man to whom they were nearer.
Those marked " inside the pyjamas " include the
few which were found on the body, an average
of less than 1 per cent in the twelve cases, and
the ones which were clinging to the garments
on the inner side. In one or two cases the men
wore undervests, and the lice upon them were
included in the count of those inside the pyjamas,
without any reference as to which garment
harboured them. These results are summarised
in the Table, in which are also included the
88 LICE AND THEIR MENACE TO MAN
approximate times at which the secondary hosts
were first bitten. The migrations of the lice are
also shown in a graphical manner in Charts I.
and II. In each of these the successive points
on the curves represent the percentages of the
numbers of lice in the following positions : (1)
inside the pyjamas of the primary host, including
the ones on the body ; (2) outside the pyjamas
of the primary host and on the contiguous
blanket surfaces, i.e. those which had left him
but had not wandered f ar ; (3) outside the
pyjamas of the secondary host and on the con-
tiguous blanket surfaces, i.e. those which had
definitely migrated and which would have pre-
sumably passed on to the secondary host for their
next feed ; (4) inside the pyjamas of the secondary
host, i.e. those which had migrated and already
established themselves on him ; (5) those which
had wandered far, and for the time being lost
themselves between the upper blankets and
which might have passed back to either host
had the experiment been more protracted ; (6)
those which were not recovered and which were
either overlooked in the search or had left the
bed. This last number was fairly constant.
The number which had wandered far on the
blankets was also fairly constant and very small,
except in Experiment 3, owing to the restless-
ness of the men disarranging the bed, and in
Experiment 4, owing to the blankets overlapping
and not completely covering one another. It
MIGRATION OF BODY-LICE 89
will be seen that the successive points on the
curves represent the relative distance of the
migration of the various numbers.
SERIES A. — In which both the Primary (P.H.)
and Secondary Hosts (S.H.) were afebrile.
Experiment 1.
Temperatures of P.H. :— 98-4°-97-8°. Skin normal.
Temperatures of S.H. :— -98-3°-98-4°. Skin normal.
The lice were released at 8 P.M., having been last fed
five to eight hours previously. They were watched for
about half an hour, during which time most of them fed
but they did not scatter. In the third hour about
twelve had crept outside the pyjamas of P.H., while
the majority were still in the original position. S.H.
had not felt any on him. In the fifth hour the lice had
nearly all left the original site, a few being outside the
pyjamas of P.H., who said he had felt them wandering
all over his back. S.H. had felt none. In the thirteenth
hour P.H. said he had felt them all over him all night
and had slept little. S.H. had slept well and did not
know he had been bitten till he awoke at dawn. He
then felt them walking on his legs and was bitten there.
In the sixteenth hour after the commencement the lice
were collected, with the following result :
184 = 92 per cent of the 200 lice were recovered. Of these,
121 =65-7 per cent were on or about P.H. ;
. 63 = 34-2 per cent were on or about S.H. ;
70 = 38-0 per cent were inside the pyjamas of P.H. ;
36 = 19-5 per cent were inside the pyjamas of S.H.
Experiment 2.
Temperatures of P.H. :— 97-l°-98-2°. Sweated a
little in the night.
Temperatures of S.H. :— 98-4°-97-6°. Skin normal.
The lice were released at 7.30 P.M., having been fed
90 LICE AND THEIR MENACE TO MAN
four hours previously. In the third hour P.H. had been
much bitten on the abdomen and flanks. Most of the
lice were near the original site, a few only outside the
pyjamas. S.H. had not felt them. In the morning
S.H. said he had slept fairly well and had not been bitten
much. He felt the first bite about six hours after the
commencement. P.H. had not slept and had been
bitten all over. In the seventeenth hour after the
commencement the lice were collected, with the following
result :
188 = 94 per cent of the 200 lice were recovered. Of these,
147 = 78-7 per cent were on or about P H. ;
41=21-2 per cent were on or about S.H. ;
79 = 42-0 per cent were inside the pyjamas of P.H. ;
10= 5-3 per cent were inside the pyjamas of S.H.
Experiment 3.
Temperatures of P.H. :— 99-0°-97-8°. Skin normal.
Temperatures of S.H. :— 98-4°-98-2°. Skin normal.
The lice were released at 7.15 P.M., having been last
fed seven hours previously. They showed no inclina-
tion to scatter but began feeding at once. In the third
hour P.H. had a normal temperature, the rise to 99°
being only temporary. Half the lice were in the original
position on P.H., who had also been bitten about the
body and on the legs. S.H. had not been bitten. In
the sixth hour P.H. was being much bitten, while S.H.
had felt none, though one or two were on the outside of
his pyjamas. He- was bitten for the first time very
shortly after this visit. In the sixteenth hour after
the commencement the lice were collected, with the
following result :
159 = 80 per cent of the 200 lice were recovered. Of these,
128 = 80-5 per cent were on or about P.H. ;
31 = 19-5 per cent were on or about S.H. ;
65 = 40-9 per cent were inside the pyjamas of P.H. ;
13= 8-2 per cent were inside the pyjamas of S.H.
MIGRATION OF BODY-LICE 91
SERIES B. — In which the Primary Host was
febrile, the Secondary Host afebrile.
Experiment 4.
Temperatures of P.H. :— 99-8°, 100-2°, 99-8°, 99-0°.
Skin dry throughout.
Temperatures of S.H. :— 98-2°-97-0°. Skin normal.
The lice were released at 8 P.M., having been last
fed six hours previously. They showed no inclination
to scatter before feeding, which the majority commenced
to do at once. In the third hour none were in the
original position. A large number were on the blankets
and outside the pyjamas of P.H. Some had already
bitten S.H. In the morning S.H. complained of being
much bitten, especially inside the thighs. In the
sixteenth hour after the commencement the lice were
collected, with the following result :
167 = 83-5 per cent of the 200 lice were recovered. Of these,
90 = 54 per cent were on or about P.H. ;
77 = 46 per cent were on or about S.H. ;
29 = 17-3 per cent were inside the pyjamas of P.H. ;
16= 9-6 per cent were inside the pyjamas of S.H.
Experiment 5.
Temperatures of P.H. :— 101-4°, 100-4°, 99-8°, 98-8°.
Skin dry throughout.
Temperatures of S.H. :— 98-4°-98-2°. Skin normal.
The lice were released at 9.30 P.M., having been last
fed six hours previously. They showed no inclination
to scatter but began feeding at once. In the third hour
P.H. had been much bitten on the body and legs. S.H.
had not felt them at the beginning of the third hour
but was bitten before its close. In the fifth hour S.H.
said he had been much bitten on the abdomen and legs,
and several lice were on the outside of his pyjamas.
There were none in the original site on P.H. In the
seventh hour S.H. was being much bitten on the abdomen,
92 LICE AND THEIR MENACE TO MAN
back, and legs. In the fifteenth hour after the com-
mencement the lice were collected, with the following
result :
179 = 89-5 per cent of the 200 lice were recovered. Of these,
101=56-4 per cent were on or about P.H. ;
78 = 43-5 per cent were on or about S.H. ;
14=: 7-8 per cent were inside the pyjamas of P.H. ;
33 = 18-4 per cent were inside the pyjamas of S.H.
Experiment 6.
Temperatures of P.H. :— 103-4°, 102-7°, 100-4°. Skin
dry and burning for the first three hours, then
moist with sweat.
Temperatures of S.H. :— 98-8°-98-0°. Skin normal.
The lice were released at 2.15 P.M., having been last
fed seven hours previously. An unusual activity was
noticed amongst them, but about two-thirds commenced
feeding. No scattering took place during ten minutes'
observation before the men were covered up. In the
third hour, when P.H. was examined, very great activity
was noticed amongst the lice, which were running round
and round with a rapidity which we had never previously
noticed in the insects. The majority were still about
P.H., but S.H. had been bitten within an hour of the
release of the lice. In the fourth hour P.H. said he
could feel them running all over him but they were not
biting. S.H. was being bitten on the abdomen and
legs. In the seventh hour P.H. said he had been bitten
once or twice only since the last visit but he could still
feel them running about much. S.H. was being much
bitten and could feel them walking about over him.
In the eighth hour after the commencement the lice
were collected, with the following result :
179 = 89-5 per cent of the 200 lice were recovered. Of these,
93 = 51-9 per cent were on or about P.H. ;
86 = 48-0 per cent were on or about S.H. ;
52 = 29-0 per cent were inside the pyjamas of P.H. ;
26 = 14-5 per cent were inside the pyjamas of S.H.
MIGRATION OF BODY-LICE 93
In considering this last result it should be
borne in mind that the duration of the experi-
ment was only half that of the previous ones.
In spite of this, about half the lice migrated to
the neighbourhood of the second man, and the
biting on him commenced within an hour. Had
this experiment been as prolonged as were the
two previous ones, the result would have been
even more striking, while, as it was, the migra-
tion may have been retarded as the febrile man
wore a woollen undervest under his pyjamas, and
this was not removed as his fever was high and
the afternoon rather chilly. It should also be
noted that the fever in his case was higher than
in the previous ones, and in correlation with this
the lice showed the surprising activity referred
to above, and, while they fed at first when very
hungry, their first hunger appeased they ceased
to do so. In each of the other cases the primary
host was being bitten throughout the experiment.
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94 LICE AND THEIR MENACE TO MAN
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CHART I. — ILLUSTRATING THE MIGRATION OF LICE FHO.M AN AFEBBILE
MAN (P.H.) TO AN AFEBRILE BEDFELLOW (S.H.).
96 LICE AND THEIR MENACE TO MAN
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CHART II. — ILLUSTRATING THE MIGRATION OF LICE FROM A FEBRILE
MAN (P.H.) TO AN AFEBRILE BEDFELLOW (S.H.).
MIGRATION OF BODY-LICE 97
Summary. — The lice were placed on the
primary host at the beginning of the experiment,
being emptied into a heap on his skin, and had
not settled down there as in the case of a man
in a normal lousy condition. The results must
not be taken to mean that under natural condi-
tions the migration of lice from a man in bed
would necessarily be as high as the experiments
indicate. That some migration would occur
under natural conditions in bed is, however,
certain, since there is no obvious reason why
these should have been averse to the quarters
allotted them on the normal men. Incidentally
also, the experiments emphasise the importance
of treating the blankets of lousy men in any
scheme of disinfestation.
There was a very marked difference in the
behaviour of the lice in the two series of experi-
ments. This difference was marked by the in-
creased migration from the primary host when
he was febrile. This will be seen by reference to
Chart III. In this chart the points on the
curves represent the migrations of the lice to
the same points as in Charts I. and II. The
continuous line represents the wanderings of the
600 lice used in Experiments 1 to 3, while the
broken line represents the wanderings of those
in Experiments 4 to 6. From this it will be seen
that when both men were afebrile, 62 per cent of
the lice remained on or near the primary host,
35*5 per cent being inside his pyjamas, while
H
98 LICE AND THEIR MENACE TO MAN
only 20 per cent passed on to or near the secondary
host, 9 '5 per cent of these being inside the pyjamas.
When the primary host was febrile 44 per cent
Lice.
Lice.
3 J
352
3 OX
10Z
153:
10%
5%
CHART III. — ILLUSTRATING THK EFFECT OF FEVER ox THE
MIGRATION OF LICE.
The continuous line represents the migration when both Primary
Host (P.H.) and Secondary Host (S.H.) were afebrile.
The broken line represents the migration when the Primary Host
(P.H.) was febrile and the Secondary Host (S.H.) afebrile.
Each curve represents the movements of 600 lice.
of the lice only remained on or near him, 15*5
per cent being inside his pyjamas, while 38*5
per cent passed on to or near the secondary host,
12'5 per cent being inside his pyjamas. The
MIGRATION OF BODY-LICE 99
febrile condition of the primary host nearly
doubled the migration. Where the primary host
was febrile the second man felt the biting of the
lice very much earlier than in the other cases,
so soon, in fact, that it is indicated that some
of the lice migrated either before they had fed
on the febrile man, or at any rate before they
had obtained a full meal. Where the first man
was normal the interval before the second was
bitten was such as to have allowed them to be
ready for a second meal after having fed to
temporary repletion when first released.
Conclusion. — The temperatures attained in the
sufferers from the three diseases carried by lice
and characterised by a febrile condition are :
typhus fever 103°-104°, sometimes 105°; re-
lapsing fever 104°-105° usually ; trench fever
commonly 103° and often 104°. It may there-
fore be taken as proven that the fevers of these
maladies tend to increase greatly the shedding
of the lice from the patients, quite apart from
their deaths, and that this phenomenon is partly
accountable for the rapidity with which louse-
borne epidemics spread.
CHAPTER IX
RELAPSING FEVER
RELAPSING fever is the name given to a disease
which is characterised by an intermittent fever
and is caused by a parasite known as a spirochaete.
To-day in Europe it is common in Poland, Russia,
parts of Austria and the Balkans. In Western
Europe it has become very rare in recent years
though occasional cases still occur in Ireland.
It is found over the greater part of Africa in one
form or another, over all Asia except the most
tropical parts, and in South America. In North
America cases are occasionally recorded, but
the disease has never established itself there.
Australia has always been apparently free of it.
It is a malady of the colder part of the year rather
than of the hotter, and epidemics rage chiefly
amongst people of the poorer classes. The epi-
demics have usually been associated with some
period of special distress such as a famine, and
the disease is sometimes known by the name of
" hunger typhus." The characteristics of the
sickness vary in the different areas, but to so
RELAPSING FEVER 101
small an extent that most authorities are now
agreed that they are variations of the same
disease. There may be a number of relapses at
quite definite intervals in the course of the sick-
ness, and during the intervals the patient often
feels well enough to go about. In the European
form of the disease there is not usually more than
one relapse after the initial attack.
About fifty years ago a German worker,
Obermeyer, when examining the blood of a case
of relapsing fever saw the minute organisms
known as spirochaetes there for the first time.
The word spirochaete means " spiral hair " and
was given to these organisms on account of their
shape. A considerable number of spirochaetes
are now known, and a few of them have been
proved to cause diseases in man. There has been
much controversy as to whether they are members
of the Bacteria, which are classed with the
Vegetable Kingdom, or of the Protozoa, of the
Animal Kingdom, or whether they belong to
neither. Those best qualified to come to a
decision are to be found speaking on either side
and the question must be considered unsettled.
Generally speaking, in structure they resemble
the Bacteria, and in their life-history Protozoa,
but as in some stages they are so minute that
they escape the microscope altogether it must be
admitted that some of the details of their life-
history are based on assumption. The spiro-
chaete is a ribbon-shaped thread-like organism
102 LICE AND THEIR MENACE TO MAN
thrown into waves which are nearly in the same
plane, like those of a swimming eel, so that it is
not a true spiral. When stained in microscope
preparations it is seen to have a core of material
which takes a deeper coloration than the envelop-
ing outer sheath. It has, however, no definite
nucleus as most Protozoa have. It swims actively
about backwards or forwards by means of a cork-
screw movement or in waves. It multiplies by
splitting either along its whole length or across the
middle. At times at one end a small granular
swelling is seen, or the whole organism appears
to split up into granules. It is considered that
these granules represent a stage in the life-history
and that they grow again into typical spirochaetes,
but the actual change has not been observed.
The spirochaete which is the cause of relapsing
fever is known as Spirochaeta recurrentis, this
name being given to it as it cannot be found in
the blood between the bouts of fever but recurs
when the disease relapses. The parasite is found
not only free in the blood but also in the cells of
certain tissues, including the white cells of the
blood and sometimes in the red cells.
Shortly after Obermeyer reported his discovery
it was shown that if the blood of a relapsing fever
patient was injected into a healthy man the latter
developed the disease. Following on this it was
found that the disease could be transmitted
similarly to monkeys, rats, and several other
animals, and that the parasite could be demon-
RELAPSING FEVER 103
strated in their blood. This paved the way for
further research, but no further discovery of
importance was made until the present decade
in regard to the European form of the disease.
Meanwhile in Tropical Africa two workers,
Doctors Button and Todd, who had been sent
out by the Liverpool School of Tropical Medicine,
were studying the form of relapsing fever found
there, and which Todd thinks is identical with that
of the rest of the world. In Central Africa there
exists a tick called Ornithodorus moubata which
has habits similar to those of a bed-bug ; that is,
it lives in cracks in the walls and floors of the
native huts and issues forth at night to suck
blood. Full-grown it is about the size of a large
pea ; its skin is tough, grey, and wrinkled, and
it is able to survive many months without taking
food. Some of these ticks were fed on cases of
relapsing fever and afterwards on susceptible
animals, and these in time developed the disease.
It was also found that the offspring of such
infected ticks (to the third generation) could
similarly transmit the malady, the spirochaete
passing in some form from the parent to the egg
and so to the young. Judging from the analogy
of what was then known of the mode of trans-
mission of diseases by insects, the investigators
naturally thought that it was by means of the
bite itself that the virus was injected into the
blood. Some of the infected ticks were brought
to the Liverpool School, and a great deal of work
104 LICE AND THEIR MENACE TO MAN
was done with this strain of the parasite.
Attempts were made to transmit it by the bites
of other vermin, fleas, lice, and bed-bugs. None
of these were successful, with the exception of one
experiment of Nuttall's, in which a bed-bug was
allowed to partly feed on an infected animal and
then to complete its meal on another animal
while its proboscis was still wet with the blood
of the first. The second animal developed the
disease, but this did not suggest that this was a
normal mode of conveyance of the disease in
nature. It was therefore concluded that the
bites of these vermin did not transmit relapsing
fever. Todd now thinks that it is not the actual
bite of the tick either which causes it. While the
tick is feeding, an operation which occupies two
or three hours, a quantity of fluid flows from two
glands on the lower side of the body and forms a
film between it and the skin. At the same time
it discharges from the anus a small quantity of a
whitish excrement which mixes with the fluid.
Both the fluid and the excrement contain small
spirochaetes, and these probably penetrate the
wound caused by the bite, thus causing the
disease.
Though the bites of lice did not cause relapsing
fever it was still thought that the vermin had
some connection with the disease, and this was
finally proved to be the case by Dr. Sergent,
working in Algeria, where it is almost constantly
epidemic. He showed that if body-lice were fed
RELAPSING FEVER 105
on a relapsing fever patient and were afterwards,
under certain conditions, crushed and rubbed into
a scratched surface of the skin of a healthy man
or animal, the latter will develop the disease.
The parasite is equally able to pass through the
unbroken moist membranes of the body such as
the eye and the inside of the nose. The dissection
of the lice which had fed on the infected blood
showed that the spirochaetes in the gut become
rapidly immobile, appear to degenerate, and
within twenty-four hours have all disappeared.
For the next seven days no spirochaetes can be
found in the louse. About the eighth day they
reappear in the coelomic cavity, that is, the space
between the gut and the body wall. This phe-
nomenon takes place in about 20 per cent of the
lice which have taken the infecting feed. The
parasites are at first very small and thin, but
they grow to that size which they develop in the
blood of man. By the twentieth day from that
on which they fed on the relapsing fever patient
they have all again disappeared. Throughout
this period a person may feed the infected lice on
himself with impunity, as the bite of the insect
is harmless. For the disease to be caused the
louse must be crushed so as to release the para-
sites which are contained in the body of the
insect and which do not appear to pass out unless
its skin is broken. A man therefore inoculates
himself with the disease by scratching the bites
and at the same time crushing the louse. The
106 LICE AND THEIR MENACE TO MAN
lice are capable of transmitting the disease at
two periods, firstly, just after they have imbibed
the infected blood, and secondly, after the elapse
of two or more days. They are most infective
on the sixth day after the infection, just before
the spirochaetes reappear in them, and from this
time the infectivity becomes less until it ceases
altogether. As in the case of the tick the off-
spring of the infected lice are capable of passing
on the disease.
Isolated cases of relapsing fever are not of
themselves serious things. An average healthy
person would not as a rule die from it and it does
not usually leave serious after-effects. The drug
salvarsan nearly always aborts an attack in a few
hours and cures the disease, subsequent relapses
being rare. The danger of isolated cases occur-
ring in a country is that in times of misery and
distress, in war and in famine, vast epidemics are
liable to break out. They are the sparks amongst
the tinder, and wretched conditions of life are the
wind that blows the sparks into flame. Then,
when doctors and nursing staffs are overworked,
and the sick, ever increasing, in their already
enfeebled condition are unable to throw off the
complaint or to receive careful attention, the
mortality may be truly frightful. The great
epidemics are usually associated with those of
typhus, since the conditions favouring the spread
of both diseases are the same, as are also, very
largely, the areas where they occur. Chart IV.
RELAPSING FEVER
107
shows such an association of the two diseases in
the recent Roumanian epidemic. The relapsing
fever commenced rather before the typhus, and
* * FEBRUARY MARCH APRIL MAX
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CHART IV. — CURVKS OF THE INCIDENCE OF TYPHUS AND RELAPSING
FEVER IN THE SECOND ROUMANIAN ARMY, SHOWING THE ASSOCIA-
TION BETWEEN TWO LOUSE-BORNE DISEASES. (After Wells and
Perkins.)
its spread was more rapid, so that it reached its
maximum in April and was declining quickly in
the following month when the typhus epidemic
reached its climax.
CHAPTER X
TYPHUS FEVER
TYPHUS fever, or, to give it its full name, Typhus
exanthematicus, is a disease which works terrible
havoc when it becomes, as it is so liable to do,
epidemic. It is characterised by a high fever
which lasts for about a fortnight, and a rash,
with all the usual manifestations of acute blood-
poisoning. The mortality is rather high, as no
treatment has yet been found which will prevent
the disease from running its normal course.
Careful nursing and plenty of fresh air are essential
to its successful treatment.
It has been said that a full history of typhus
fever since the Middle Ages would be a history
of Europe, so closely have the vast epidemics
been associated with wars and famines, and so
hard on the heels of improvement in social con-
ditions has followed the abatement of the disease.
The peoples who lag behind in the improvement
in housing and general sanitation reforms are
those who still suffer from the ravaging epidemics.
Thus in Great Britain and the Western part of
Europe generally the disease has almost dis-
TYPHUS FEVER 109
appeared, but in Ireland and in Brittany it still
lingers endemic, that is, sporadic cases occur which
are not due to the immigration of an infected
person, but which show that all the essentials
for the disease are constantly present. These
essentials are, firstly, the presence of lice, and
secondly, the actual causative agent of the
disease, whatever that may be, lingering either
in the lice or in the bodies of those who have once
suffered from the malady. To develop an epi-
demic from these sporadic cases, conditions of
unclean living and poor housing, together with a
general infestation of lice among the population,
are essential. The disease is one which is mainly
confined to cold and temperate climates, and
those parts of the Tropics where the heat is not
intense. In a country such as Mexico the
epidemics occur on the hills and not in the hot
low-lying coast towns. Similarly in temperate
countries the epidemics rage more fiercely in
the winter than in the summer. With the ex-
ceptions mentioned, typhus has been recorded
from the greater part of the world, though
Australasia, with the exception of the Celebes
Islands, appears to have been spared its ravages.
Outbreaks of the disease have not always been
recognised as such, probably because the char-
acteristic rash is not obvious on dark skins, and
also because diagnosis must rest on symptoms,
since modern methods in medicine have failed
to find a means of recognising the complaint
110 LICE AND THEIR MENACE TO MAN
either by the microscope or by the reactions of
the blood.1 At the present day it is most common
in Poland, Russia, Austria, and Eastern Europe
generally, the cooler parts of Asia, Northern
Africa, and Mexico. It is uncommon in Canada, the
cases which are occasionally reported there being
due to small foci of infection set up by infected im-
migrants, and the conditions in the country not
being suitable to widespread epidemics. The
same remark applies generally to the United
States, though it is definitely established in New
York, where it is known as Brill's disease.
That the causative agent of the disease is
present in the blood was shown by Moczutovski,
who inoculated himself with such blood, suffered
from the sickness, and later unfortunately died
from the results of the attack. It was later
shown that monkeys and rabbits could be in-
fected with the disease by inoculation.
In spite of much careful searching by many
brilliant workers the actual agent which causes
the disease, that is, the organism which must be
present, and multiplying in the body of the patient
to cause the intense blood-poisoning, has not yet
been certainly discovered. It is improbable that
this discovery will be long delayed. Various
organisms which have been found in the blood
or other tissues have at different times been
described as the causative agents, but no proof
has been forthcoming.
1 The Weil-Felix reaction now appears to be an established test.
TYPHUS FEVER 111
An investigation into the possible association
of body-lice with typhus was made by three
French doctors, Nicolle, Blaizot, and Conseil.
Body-lice were fed on men and monkeys suffering
from typhus, and after a period of a week, during
which the virus was developing in them, they
were found capable of infecting, by means of
their bites, other monkeys on which they were
then fed. It was also shown that if the gut con-
tents of such infected lice were removed and
spread over a scratched area of skin on a healthy
monkey, it developed the disease. It was further
proved that if the excreta of the infected lice
were collected and inoculated by scratching, an
attack of the disease followed. Head-lice equally
with body-lice are able to transmit the malady.
It would appear that the offspring of the in-
fected lice are not, as in relapsing fever they are,
themselves able to hand on the disease, though
this is still disputed, one experiment having
had a positive result and many negatives being
required to discredit one positive.
As soon as this association between lice and
typhus fever was proved, all that was known
about the spread of the disease fell into line. The
theory most popularly held had been that the
virus was air-borne, but that a short passage
through air sufficed to kill it, a close approxima-
tion of the healthy to the infected person being
therefore necessary. It was now seen why in
times past doctors and nurses were so liable to
112 LICE AND THEIR MENACE TO MAN
contract the complaint, and why with more
modern methods of cleansing the patients on
admission to hospital this so rarely happened ;
why those who first handled a patient or his
rejected clothing were so likely to develop it ;
why it was dangerous to sit on the bed of a
typhus case ; why cold rooms containing the
patients were less dangerous to those entering
than hot stuffy ones in which lice would be prone
to wander ; why sporadic cases were not un-
common among dealers in old clothing. The
larger aspects of the epidemiology of the disease
also became clear. In the great epidemics the
people who had been most attacked were those
who lived under congested conditions, and people
of the tramp class. These are just the ones
most liable to harbour lice. Those living in one
house might be attacked and those in an adjoining
house spared, if they were not on friendly terms
and interchanging visits, that is, if there was
no opportunity for the passage of lice between
them. Epidemics were worse in winter than in
summer, and this is the season when lice are
most numerous, because clothing is changed less
frequently and bathing is less freely indulged
in ; people keep more indoors ; crouch close
together over fires ; sleep in close proximity,
wearing all their clothing, in order to keep warm
by night as well as by day. The typhus amon^
the natives of Cape Colony was more prevalenl
also in the winter, when they slept in huts.
TYPHUS FEVER 118
than in the summer, when they spent the night
out of doors.
Why armies in the field should have suffered
so terribly from louse-borne diseases is obvious,
for always the facilities for cleanliness to which
the civilian is accustomed are lacking, and under
most conditions the troops are congested. Often
too, one may say always before the present war,
hospital accommodation has been inadequate,
sick and wounded have been crowded together
in the same waggons, have lain close together
in the same tents, often clothed still in the gar-
ments in which they fought. Dying in these
conditions, they were often not moved for hours,
and by this time the lice of the dead would have
spread themselves over the living. The great
epidemics of typhus and relapsing fever in Europe,
when whole communities have been decimated,
have generally been the sequel or the accompani-
ment of either famine or war. Before our fuller
knowledge of the mode of spread of these diseases
this was thought to be due to the reduced vitality
of the population, but this is only partly the case.
It is due to an increase in lice. When the general
commodities of life become scarce and their
prices rise, the poorer part of the population have
money for only one thing — food ! Clothing gets
worn out and cannot be replaced ; one garment
goes to patch another until the unfortunates are
left with a single outfit of rags, filthy because
soap cannot be obtained. Inevitably they be-
114 LICE AND THEIR MENACE TO MAN
come lousy, and increasingly so, since some lice
are always present to commence the general
infestation. Once introduced among them a
louse-borne epidemic spreads like wild-fire. We
in this country, and our Allies in France and
Italy, have mercifully not experienced this con-
dition of things, and are unlikely to do so, for
though the cost of things has been much enhanced,
famine prices have not been touched, and we have
still, most of us, two shirts, one on the back and
one in the wash. Our enemies have been less
fortunate. The disease was common in Europe
to the east of Germany, and naturally occur-
rences of it were not uncommon in the Russian
Army. Cases broke out among the prisoners
taken by the Germans, and epidemics started
in the prison camps, for these were much over-
crowded, and there was little facility for cleanli-
ness in them, while no encouragement to destroy
vermin was afforded by the callous authorities.
From these we know that the disease spread to
the large German cities, including Berlin and
Hamburg, but to what extent they prevailed
there we do not know. The Germans have been
forced to develop the factors necessary for epi-
demics of typhus and relapsing fever among
their civil population owing to the scarcity of
soap and of clothing.
The sad story of the Wittenberg Camp is well
known. Typhus broke out among our prisoners
there, owing to contact with Russian prisoners.
TYPHUS FEVER 115
All the German Staff, both administrative and
medical, fled at once. The authorities cut off
all necessary sanitary supplies, and forbade any
communication between the people outside and
the unfortunate prisoners. Man after man went
down before the disease, and the epidemic spread
right through the camp as the calculating
brutality of the enemy doubtless intended that
it should. Of 800 prisoners who contracted the
complaint, 300 died, a heavy mortality which
could not have been approached had any facilities
been afforded to alleviate the suffering. The
Medical Officer in charge, Dr. Aschenbach, visited
the camp only once during the six months that
the epidemic raged, and then only in a most
casual manner. When Major Fry asked him for
some simple remedies he turned away with a
muttered insult. Of the six British doctors who
grappled heroically with the disease, almost with
their bare hands, four contracted the fever, and
three, Major W. B. Fry and Captains A. C.
Sutcliffe and S. Field, died of the malady, while
Major A. E. Priestley, C.M.G., and Captains A. C.
Vidal and J. La Fayette Lauder survived the
horrors and gave to a startled world unshakable
testimony of this unspeakable atrocity. There
cannot be the slightest excuse for this cynical
proceeding. The Germans knew, as we knew,
that typhus was spread by lice, and that the
epidemic could have been cut short and stamped
out a week after its commencement by the dis-
116 LICE AND THEIR MENACE TO MAN
infestation of all the prisoners, and this they
would themselves most willingly have performed
had the necessary apparatus been provided.
Typhus also wrought sad havoc in Serbia
among both soldiers and civilians. There the
disease is endemic, a case occurring here and
there, year after year. It needed, however, the
strained conditions of war to bring it to epidemic
proportions. Three attacks from the Austrians
the brave armies of our Allies withstood, until
in a zone behind the front stretched an area of a
congested population of wounded soldiers and
refugees with all the supporting organisation of
the battle. All the large buildings were con-
verted into hospitals and were filled with the
wounded so that the medical services were
already strained to the utmost. Then this
dread enemy appeared amongst them, spread-
ing throughout, and the Austrians, taking ad-
vantage of the advent of this most loathsome
ally, were able to sweep through the country,
overcoming for a time, but never breaking, the
spirit of this proud little nation.
To Doctors H. G. Wells and R. G. Perkins of
the American Red Cross Commission in Roumania
we owe an excellent account of the rise and fall
of one of the worst epidemics of louse-borne
diseases which have ever raged, at any rate in
recent years. This followed on the invasion of
Roumania and the consequent retirement of the
army, and the flight of the civil population
TYPHUS FEVER 117
before the invading hordes. In Moldavia, a
territory normally occupied by about two and
a half million people, the population was tem-
porarily doubled by the retreat and the presence
of about a million Russian troops. Food was
naturally scarce when so many extra mouths had
to be filled, and as it was winter the absence of
fuel was bitterly felt, while transport was in-
adequate. The numerous refugees, ill-clothed
and badly nourished, were in a pitiable state,
crowding together in their dirty rags, and with-
out blankets to keep out the cold. Early in the
winter relapsing fever made its appearance and
spread rapidly, while in February the more
terrible typhus also began to rage in a country
where it was previously almost unknown, and
consequently was not at first recognised. Both
diseases continued to spread, and increase into
April and May, when warmer weather and some
return of organisation led to their control.
Wells and Perkins write : l " Now arose a
situation that can only be compared to the
descriptions in Defoe's Journal of the Plague
Year. The stricken population fled hither and
thither to escape infection, or to find food,
warmth, and shelter, and so they spread the
disease until it is probable that nearly a million
were infected in a population, including the
armies, of something less than 5,000,000. Stories
are told of horrors piled on horrors — of trains
1 The Journal of the American Medical Association, March 16, 1918.
118 LICE AND THEIR MENACE TO MAN
stagnating on congested tracks, while in box
cars the people were packed so closely together
that those who died could not fall, and were
removed only when at last the cars were emptied ;
of morning searches of the railroad stations and
freight yards for the bodies of persons who had
crept into corners and expired ; of daily sights
of people dying in the streets of Jassy, some
from disease and some merely from starvation
and exposure. Every hospital and improvised
barrack was swarming with typhus cases, and as
at first the rush of trouble was too great to permit
of prophylaxis, infection spread throughout the
buildings, taking not only wounded soldiers, but
also doctors, nurses, orderlies, and all divisions
of the hospital personnel. In all places the same
story of horrors is told. In all, the shortage of
beds was so great that usually two beds were
placed together to hold three patients across
them, while often two more patients were laid
on the floor underneath. So short-handed were
the hospitals that sometimes it was hardly possible
to do more than to pick out the dead to find
place for those who were still living. It is said
that in the little city of Jassy as many as 500
died in a day. . . Especially disastrous were the
first barracks erected for the retreating army.
To gain warmth they dug into the ground with
only the roof above the soil, and the men slept
on a layer of straw covering the floor, lying
close together for warmth. In these places
TYPHUS FEVER 119
infected lice had an uninterrupted march from
one end of the place to the other, and the men
came down by scores. And so in the course of a
month the disease had spread throughout the
country, adding a supreme misery to already
unbearable conditions." Owing to the im-
possibility at the first rapid spread of the epi-
demic of making any arrangements for the
disinfestation of the patients admitted to the
hospitals a sad proportion of the medical and
nursing staff became sufferers from the disease,
and 200 of the 1200 medical officers in the
country died from typhus. The authors above
mentioned pay tribute to the devotion of those
whose duties took them amongst the sick, while
the Queen went in and out of the wards regard-
less of the grave risk. Though the warmer
weather of early summer made life a little more
bearable for the suffering people, and prevented
the peasants from herding together so much,
thus, together with active measures against the
lice, reducing the violence of the plague, it did
not entirely cause its disappearance. Sporadic
cases continued to occur here and there through-
out Moldavia, and it is probable that typhus
for a time will be endemic in the country, since
the Roumanians are an agricultural people with
the habits of peasants and, though not averse
to cleanliness, will probably have a difficulty
in eradicating the large increase in lice which
these terrible times produced.
CHAPTER XI
TRENCH FEVER
By Major W. BYAM, R.A.M.C.
IF not a new disease, at any rate a disease with a
new name, has come into prominence during the
Great War. As this disease was first recognised
by us among men in or near the trenches in
France, we gave it the name of Trench Fever.
So striking was the localisation of the trouble
that it was felt for a long time that the trenches,
or conditions of trench life, were essential to the
production of this illness. We now know better,
for it has been proved beyond doubt that the
lice that infest so many of our soldiers are re-
sponsible for the carrying of the disease from
man to man. At the same time we see why
the trenches came to play so important a role
when the disease first made its appearance, for
it requires but little imagination to realise that
the man in the fighting line would be the first
to become lousy. While face to face with the
enemy and living the life of the trenches, clean
clothes and hot baths are luxuries to be dreamt
TRENCH FEVER 121
of but in vain, and without them men become
verminous no matter who they are if one arrives
amongst them with a louse upon him. Another
factor also played a part in causing the trenches
to spread the malady, for in them men live and
sleep in the closest contact, and so it is that lice
find no difficulty in passing from man to man,
from the diseased to the future victim. As
time went on the number of men carrying the
germ of trench fever in their blood gradually
increased, men infected passed to other areas
than the foremost lines, and lice in many quarters
had an opportunity of feeding on them, such
lice in their turn becoming disseminators of the
fever. In this way the disease spread, and
attacked men in the field hospitals, in billets,
rest camps, and any place where the two essentials
for its production were present — men with trench
fever in their blood and lice to pass it on to others.
Besides being erroneous the giving of this name
' trench fever " may prove a serious mistake.
To those unfamiliar with the disease the man
who has never been in the trenches cannot be
suffering from trench fever, and for this reason
the spread of the disease to new districts, and
among those unfamiliar with its symptoms, will
go unrecognised. Should trench fever spread
amongst us at home, think how unfortunate such
a name might prove to be.
That trench fever might come amongst us
is no idle supposition. Many lice are always
122 LICE AND THEIR MENACE TO MAN
present in poorer districts and places where
facilities for cleanliness are limited, and unless
great care is taken our fighting men will bring
home many more. Men still capable of infecting
lice that feed on them are returning to their
homes every day, and will continue to do so until
the disease can be stamped out, or such a treat-
ment for the sufferer discovered that his blood
is truly freed from the infection. So far the
trouble has been by no means confined to our
armies alone. The enemy, who suffers from it
too, named it " Volhynia fever," and sometimes
" five day fever." The first shows us how
widely spread the illness is, the second merely
draws attention to a characteristic of the disease
which is by no means constant. Neither name
is very helpful, or likely to survive when once
we know the nature of the germ which produces
the illness.
As men have passed from front to front they
have taken trench fever with them, till we can
say with certainty that all the European theatres
of war are involved and that the disease has
appeared in Egypt and possibly in Mesopotamia
also. There was a time when some amongst us
might have thought that this mattered little, as
an attack of trench fever was but a simple affair,
short-lived and soon forgotten. Even had this
been so, the temporary loss in man power to our
armies must have been immense ; but ask the men
who have suffered from trench fever what they
TRENCH FEVER 123
think. Some will tell you that they had fever,
very like " flue " or " their old rheumatism " for
a few days, and then got back to work ; others
will say that though the illness was unpleasant
while it lasted they recovered pretty well and
now only get returns of the old pains on damp
days ; but here and there will come a sufferer
who is quite sure that he " has never been the
same man since." Such men as the last will
complain of pain and tenderness in the shins,
particularly in the evenings or after even a
moderate walk; of rheumatic-like pains in the
muscles of the limbs or back, and sometimes of
similar pains in or around the joints ; of being
generally below par and underweight ; of getting
easily fatigued and short of breath on slight
exertion ; of having headaches ; of feeling depressed
and nervous, so that things that used to have no
effect on them are now actually frightening; of
difficulty in getting off to sleep at night, with the
result that they cannot rouse themselves at the
usual hour in the morning ; of palpitation or pain
over the heart, cold and sweaty hands and feet,
and a general tendency to perspire that is quite
unnatural to them. It is not usual for a man to
tell you of all these things, and sometimes he will
be content to say that he just feels " rotten,"
but in any case you will have no doubt in your
own mind that the man feels far from well.
This state of invalidism may have already lasted
for months, and of the questions that the future
124 LICE AND THEIR MENACE TO MAN
alone can answer are — how much longer may it
last ? what may it lead to ? At any rate we know
that in the bodies of such sufferers the germs of
trench fever continue to exist, and that from time
to time the disease flares up, giving rise to bouts
of fever, with the old pains and depressing after-
effects, which are apt to be mistaken for attacks
of influenza or rheumatism.
But if this is trench fever in its latest and
most obstinate form, how does it appear at the
onset ? Like the familiar " flue," trench fever
is often upon one most unexpectedly. It is no
unusual thing for a man to start the day in his
accustomed good health and to be in the midst of
his work when he is suddenly stricken down with
severe headache behind the eyes, giddiness, weak-
ness in the legs, and pain all over. So sudden may
be the onset that a man may fall out of the saddle,
or while walking become so weak and giddy that
he has difficulty in dragging himself home to bed.
In other cases coming events cast their shadows
before them, and the victim feels " out of sorts "
and complains of headaches for a day or two
before the fever has him down. When once in bed
the patient finds that he is unable to lie still
because he aches all over the small of his back and
limbs, his temperature rapidly mounts and may
reach 103° or 104° F. or even higher, his tongue
is slightly furred, his eyes become pink, and he
passes a most uncomfortable day, becoming worse
towards evening, when his mind may wander,
TRENCH FEVER 125
and gets no restful sleep throughout the night.
As the hours go by his skin begins to grow moist
and the pains easier, so that during the following
morning comparative comfort is once more re-
gained. But the respite is usually short and
once more the fever comes on as night approaches ;
this time the pain is often not so general but
seems to settle in the forehead, small of the back,
and legs. The shins in particular are the seat of
trouble and often feel as if they were suffering
from toothache. Again the night is one of
wretchedness and all desire for food has passed
away ; sweating occurs at intervals and may be
profuse, but with it usually comes relief and
eventually comfort. On the third evening the
fever reasserts itself once more, but rarely with
the severity, of the first two days, and after that
recovery is usually rapid. It is not every one
who suffers so severely, yet on the other hand
some continue to have fever after the usual three
days. A few are lucky and escape with this one
bout, but most relapse towards the end of a week
from the original onset of the trouble, and go
through a somewhat similar experience to that
just described. After three weeks most trench
fever sufferers are sufficiently recovered to return
to work, but others, as already described, pass
gradually into a condition of chronic aches and
pains, with bursts of fever from time to time.
These late fever waves are generally quite short,
lasting but a few hours in many cases ; they some-
126 LICE AND THEIR MENACE TO MAN
times recur at such regular intervals that the
patient can foretell his day of trouble. Every
fifth day the fever may return, and so we see the
reason for one name the Germans give to the
disease, but most often the periods vary and each
successive interval tends to become longer than
the last.
Now let us turn to the louse once more and
see the part it plays in spreading this disease that
has caused so much suffering. Experiments per-
formed by McNee and others proved that the
germ of trench fever was in the blood of the
patient during his attacks of fever. The question
was, How did this germ leave the sick man and
enter the healthy ? Our recent work, carried out
for the War Office Trench Fever Research Com-
mittee, has done a good deal to clear this mystery
up. Several very gallant men came forward to
help us in our task, and it is not too much to say
that without such help we would have found out
nothing, since experimental animals, which are all
apparently resistant to trench fever infection,
could not be used. These men volunteered to
let us try to give them trench fever in any way
we thought the disease might spread naturally in
the field. The first two men to come forward
were W. H. Cole and H. H. Edgeler, and to them
great credit is due, as the work for which they
offered themselves might, for all they knew, be
productive of most unpleasant consequences.
Attempts were made to convey trench fever to
TRENCH FEVER 127
these two men by allowing lice taken from trench
fever patients to feed on them. Nothing hap-
pened though the experiments were continued
for many weeks, but as we anxiously watched
the men from day to day we were struck by the
fact that they never scratched their skin where
the lice had bitten. Now the average soldier
suffers considerably from the irritation of the
lice upon him and scratches himself accordingly.
It occurred to us, therefore, that herein might lie
the explanation of what, at first, seemed a dis-
appointing failure. Cole and Edgeler were old
and tough ; the man of military age had a skin
that was far more irritable. The latter scratched
himself ; our volunteers did not. Was scratching
an essential to infection ? To test this possibility
the skin of a new volunteer named D. Sullivan
was on 5th February 1918 scratched by means of
a needle, and the droppings of the lice feeding on
Cole and Edgeler rubbed into it. A week later
Sullivan developed trench fever, and as a result
the usual method of transmission of the disease
had been demonstrated, for we have repeated this
and similar experiments many times since with
unfailing success. Further work, however, has
shown that men bitten by infected lice, but who
do not scratch themselves, may in some instances
contract trench fever. Such happenings are the
exception and not the rule, and are probably the
result of lice depositing their droppings on the
openings made in the skin by their own bites.
128 LICE AND THEIR MENACE TO MAN
These droppings are partly fluid when passed by
the lice, and may be supposed to enter the minute
punctures in the skin as they do the lesions caused
by scratching. The fact that men who do not
scratch themselves when bitten by infective lice
develop trench fever at widely varying intervals
of time from the day when such lice begin to feed
on them, is strong presumptive evidence that it
is not the act of biting which conveys the disease.
Such infections have been produced after periods
varying from sixteen to thirty-five days, whereas
when droppings are rubbed into the broken skin
the interval which elapses before the fever
manifests itself is remarkably constant and is
usually eight days. Even when dry these drop-
pings have by no means ceased to be a danger as
the disease germ continues to exist in them, and
only awaits a suitable opportunity to flourish in
another man. Droppings in this state may
remain in clothes or blankets for weeks or months
and be eventually rubbed or shaken into wounds
or scratches of one who has never known a louse.
We have ourselves kept droppings of lice for
four months and then produced trench fever by
introducing them into the skin of a healthy man,
which shows how truly infectious they are. And
skin wounds are not the only portals for this
poisonous dust, the delicate membrane of the
eye being an equally open door. Only allow
the fine particles to get blown upon the eyeball,
and trench fever may be the consequence as we
TRENCH FEVER 129
have proved. In this we see how dangerous a
proceeding may be the homely shaking of a
blanket used by one who is lousy and a sufferer
from the disease.
Adult lice, given two full meals a day and kept
at the temperature which exists inside the clothing,
each produce daily about eighty fragments of the
granular dust into which the excreta ultimately
breaks up (Fig. 9). The female louse produces
rather more than the male. One thousand of these
granules weigh three milligrams. During its life
of about forty days the louse therefore produces
about ten milligrams. Since it may be transmit-
ting trench fever for the whole of its life, after
the shorter or longer incubation period of the
virus of the disease in its body, practically the
whole of this dust may be of a most dangerous
nature, and since we have shown that one-tenth
of a milligram is enough to cause an attack of the
disease a single louse may produce sufficient to
infect almost a hundred men. A soldier who
harbours in his clothing five hundred lice, a by
no means exceptional number, and has the trench
fever germ in his blood, is the indirect means of
producing enough infected louse excreta daily to
cause an attack of the disease in every man in his
battalion, and while much of this is retained in
his own clothing much of it is also spread abroad
and falls on his comrades.
But still, without the lice there could be no
droppings, so that all our energies should be
K
130 LICE AND THEIR MENACE TO MAN
directed to the destruction of the pest if we would
save our armies from a disease which lays low
so many of our men, and also protect our children
from the evil that might descend even unto the
third and fourth generation.
INDEX
Abdomen of body-louse, 14
of crab-louse, 78
of head-louse, 69
African relapsing fever, 103
Alimentary canal, 15
American Red Cross Commission,
116
Anatomy of body-louse, Figs. 1
and 3, l!2
of crab-louse, 77
of head-louse. (.9
Anoplura, 1, 2
Antennae, 12
Armies, disinfestation in, 45, 51,
64
ideas on lice in, 6, 11, 46
inspections in, 65
louse-borne disease in, 113, 116,
118, 120, 122
lousiness in, 41, US
Armpits. See Axillary hair
Aschenbach, 115
Axillary hair, crab-lice on, 79
lice on, 65
Bacot on disinfestors, 58
on fecundity of body-louse, 32
on Pediculus humanus, 3, 69
on repellants, 60, 62
Baking oven disinfestor, 50
Barrel disinfestor, Fig. 10, 52, 54
Baths, not eradicating lousiness,
5, 64
Beard, crab-lice on, 79
Bed-bug contrasted with lice as
regards rinding host, 36
infesting dwellings, 39
irritation of bite, 7
relapsing fever transmitted by,
104
Beds, disinfestation of, 64, 97
lice spread by, 36, 30
lice in, movements of, 97
Belts, impregnated, 60
lice biting near, 27
Birch tar oil, 60
Bites of lice, 6, 27, 41, 127
relapsing fever and, 104
trench fever and, 127
typhus and, 111
of tick, relapsing fever and, 103,
104
Biting lice, 1
Blaizot on typhus, 111
Blankets, eggs of louse on, 40
importance of disinfesting, 64,
97
Blood of louse, 18
relapsing fever conveyed by, 102
sucking lice, food of, 2
trench fever conveyed by, 126
typhus conveyed by, 110
Blue patches, crab-lice causing, 83
Body, inspection of, 64
Body hair, characters of, 79
eggs of lice on, 21, 42, 64
crab-lice on, Fig. 7, 79, 81
lice infesting, 70, 75, 79
removal of, 64
shedding of, 81
Body-louse, anatomy of, external,
Fig. 1, 12
internal, Fig. 3, 15
breeding of, 31, 32
characters of, 11
diseases carried by. See Diseases
dissemination of, 34
eggs of. See Eggs
excreta of. See Excreta
feeding of, 27
geographical distribution of, 43
habits of, 21
host, finding, 36
ignorance about, 4
increase of, causes of, 6, 41, 113
rate of, 32
winter, in, 43, 112
infestation, 41 . See also Infesta-
tion
interbreeding with head-louse,
69
irritation caused by, 6
132 LICE AND THEIR MENACE TO MAN
Body-louse (conld.) —
life-history of, 24
migration of, 36, 84
prevalence of, 3, 35
rearing of, 32
relapsing fever transmitted by,
104
trench fever transmitted by,
121, 127
typhus transmitted by, 111
Boiler disinfestor, 50
Boiling water destroying lice, 48
Bot-flies, dissemination of, 35
Brill's disease, 110
British Medical Sanitary Mission,
52
Bronzing of skin, Fig. 2, 7
Brushes, disinfestation of, 62
eggs of hog-louse on, 23
Brushing, disinfestation by, 18, 45
dislodging lice, 36
Butter, rancid, 61
Byam, Major W., 84
Carbolic acid, 603 61
Cement of eggs of body-louse, 19,
21
of crab-louse. 79
Chambers, hot air, 58
steam, 55
Chitin, 11, 25
Circulatory organs, 18
Claw of body-louse, ]4
of crab-louse, Fig. 13, 77
Cleansing stations, army, 51, 65
municipal, 50
Clothing. See Garments
Coal tar products, 60
Coelom, spirochaetcs in, 105
Coitus, crab-lice spread bv. 80
of lice, 20, 31
Combing for head-lice, 73
Combs alleviating itching, 72
Conseil on typhus, 111
Conveyances, lice in, 4, 38
Copeman on naphthalene, 62
Copulatory organs, 15, 31
Corpses, lice leaving, 36, 113
Crab-louse, Fig. 12, 3, 6, 70, 76
characters of, 76
disease and, 82
disinfestation from, 63, 64, 82
dissemination of, 80
eggs of, Fig. 6, 79
habits of, 79
irritation caused by, 6
rearing of, 78
Crushing of louse and relapsing
fever, 105
Dead lice, appearance of, 50, 62
Death of louse, causes of, 33
Defaecation of body-louse, 30
of head-louse, 80
Development of body-louse, 24
of crab-louse, 80
of head-louse, 71
Digestive system, 15, 29
Dirt, relation of lice to, 4, 113
Diseases, louse-borne, 9, 100, K.8,
120
prophylaxis against, 66, 129
rapid spread of causes, 99,
106, 113, 121
salivary juice conveying, 28
Disinfection of louse excreta, 49
Disinfectors, 50
Disinfestation, 44, 97
armies, in, 46, 51, 65
blankets, of, 64, 97
body, of, 47, 64
chemicals for, 60
civilian, 50, 65
clothing, of, 44-60, 75, 82
crab-lice, from, 63, 64, 82
general remarks on, 64
head-lice, from, 64, 73
household, 50, 62
sick, of, 112
tests of, successful, 50, 58
train, 52
Disinfestors, hot air, 50, 58
loading, 59
steam, 50, 52
Dissemination of body-louse, 35
of crab-louse, 80
of head-louse, 71
of parasitic insects, 34
of trench fever, 121
Distribution. See Geog. dist.
Droppings. See Excreta
Dug-outs, infested, 39
Dutton on relapsing fever, 103
Dwellings, infested, 39
Eczema, 9
Eggs of body-louse, Fig. 5, 19,
21, 32
blankets, on, 40
clothing, on, 42
empty shell of, 23
hair of body, on, 42, 70
hatching of, Fig. 7, 23
incubation of, 23
laundry not destroying, 40
oviposition of, Fig. 4, 22
seams, in, 45
of crab-louse, Fig. 6, 79
dissemination of, 81
INDEX
133
Eggs of head-louse, 71
of hog-louse on brushes, 23
Epidemics of louse-borne disease,
9, 99, 118, 121
of relapsing fever, 106
of typhus, 108, 113, 114, 116
Epidemiology of typhus, 111
Eucalyptus, 60
Excreta of body-louse, Fig. 10,
30, 127
amount extruded, 129
garments, on, 49
scratching inoculating, 111,
127
sweat dissolving, 31
trench fever infected, 129
disinfection of, 49
typhus infected, 111
weight of, 129
of tick, 104
Experiments with lice on fevered
men, 84
trench fever, 126
Eye, body-louse, of, 14
infection through, 105, 128
Eyebrows, crab-lice on, 79
Eyelashes, crab-lice on, 79, 82
Famine, louse-borne disease and,
100, 106, 113
Fat body, 20
Feathers, disinfestation of, 62
Fecundity of body-louse, 32
of crab-louse, 80
of head-louse, 71
Feeding of body-louse, 24, 27
of crab-louse, 80
on fevered host, 99
of horse-flies, 29
of lice, 2
of tick, 29
Female louse, 14, 19, 31
Fever, crab-lice causing, 83
lice migrating in, 84
relapsing, 100
trench, 108
typhus, 120
Field, Capt. S., 115
Five-day fever, 122
Fleas, contrasted with lice as
regards control, difficulty
of, 67
feeding habits, 2, 30
finding host, 36
infesting dwellings, 39
irritation of bite, 7
longevity, 33
metamorphosis, 24
Fore-gut, 15
Fry, Major W. B., 115
Garments, discarded, lice on,
36, 38
disinfestation of. See Disinfes-
tation
dissemination of lice by, 40,
71, 81
famines, scarcity in, 113
excreta of lice on, 31, 49
infested, 41
Geographical distribution of lice,
43
relapsing fever, 100
trench fever, 122
typhus, 109
Germany, prison camps of, 9,
114
Glands of tick, secretion of, 104
Glandular troubles caused by lice,
9
Gonopods, 15, 21, 69
Grant, Capt., 52
Greases, 18, 63, 73
" Ground lice," 6
Habits of man, lice in relation to,
4, 5, 35, 72
of body-louse, 27, 31
of crab-louse, 78
of head-louse, 70
Haematopinus sui. See Hog-
louse
Haemocoele, 18
Hair, cropping of, 72. See also
Body hair
Hamar, Dr., on lice in beds, 39
Hats, eggs of lice in, 71, 75
Haustellum, 12, 28
Head, of body-louse, 1 2
of crab-louse, 78
crab-lice on, 79
head-lice on, 70
Head-lice, 3, 69
characters of, 69
disinfestation from, 73
habits of, 70
prevalence of, 3
typhus transmitted by, 101
Heart of insects, 19
Heat, disinfestation by, 46, 50, 58.
See also Temperature
Hind gut, 16
Hippoboscid flies, dissemination
of, 35
Hog-louse, eggs of, on brushes,
23
134 LICE AND THEIR MENACE TO MAN
Horse-flies contrasted with lice as
regards pain of bite, 29
specialisation to host, 2
Hot air chambers, 58
Hunger typhus, 100
Hunter, Col. W., 52
Incubation of egg of body-louse,
23
of crab-louse, 79
period in trench fever, 128
Infection of lice by relapsing fever,
104
trench fever, 121
typhus, 111
Infestation, body-louse, by, 41
crab-louse, by, 79
famines increasing, 113
head-lice, by, 3, 70
origin of, 5, 39
troops, of, 41
Influenza, trench fever resemb-
ling, 123, 124
Inspections for lice, 10, 42, 65
lodoform, 63
Ironing, 45
Irritation caused by lice, 6, 27,
71, 81, 83, 127
Itching. See Irritation
Kerosene, 62
Kit-bags, lice in, 40
Larva of body-louse, 24
of crab-louse, 79
of flea, 24
Latrines, crab-lice spread by, 81
Lauder, Capt. J. La Fayette, 115
Laundry, lice surviving, 40
Leather, disinfestation of, 50
Lefroy, Prof., 63
Legs of body-louse, 14
of crab-louse, 77
Lice, bites of. See Bites
body hair, on, 65, 70, 79
danger of, 9
dead, appearance of, 51, 62
diseases carried by, 9
ignorance in regard to, 4
migration of, in fever, 84
origin of, 5
species of, infesting man, 3
Malaria, 66
Male body-louse, 14
Mallophaga, 1
Malpighian tubes, 16
Mashakalumbwe, lice on, 72
McNee on trench fever, 126
Mercury ointment, 64, 82
Metamorphosis of body-louse, 25
of crab-louse, 25
of flea, 80
Migration of body - lice from
corpses, 36, 113
clothing, 36, 40
in fever, 84
of crab-louse, 80
Mobile disinfestors, 53
Moczutovski, 110
Monkeys, human lice on, 2
lousing, 44
Mosquitoes contrasted with lice
as regards difficulty of
control, 66
feeding habits, 2, 30
skin maggots conveyed by, 35
Moulting of body-louse, 25
of crab-louse, 80
Moustache, crab-lice on, 79
Mouth of louse, 15
N.C.I., 61, 63
Naphthalene, 60, 62, 75
Nervous system, 17
Neurasthenia caused by lice, 9
Nicolle on typhus, 111
Nits. See Eggs
Nose, infection through. 105
Nuttall on biology of crab-louse,
78, 81
on coitus of lice, 31
on dry-storage of clothing, 46
on hatching of egg, 23
on oviposition of louse, 21, 70
on Pediculus humanus, 3
on transmission of relapsing
fever, 104
Nymph,. 26
Obermeyer, 101
Oesophagus, 15
Offspring of infected lice, 83, 111
of ticks, 103
Oils, 18, 63, 73
Ointment naphthalene, 62, 75, 82
mercury, 64, 82
Operculum of egg of body-louse, 21
of crab-louse, 79
Ornithodorus moubala, feeding of,
29
habits of, 103
relapsing fever transmitted by,
103
Orr, Capt. H., 52
Ovaries, 19
Oven, 50
Oviposition, 21
INDEX
135
Paraffin, 62, 75
Parasites, dissemination of, 35
of relapsing fever, 101
Peacock on disinfestors, 52
on eggs on blankets, 40
on locomotion of lice, 38
on lousiness of troops, 41
on N.C.I., 63
on senses of lice, 37
Pediculus capilis, 3, 69
corporis, 3, 11, 21, 34
humanus, 3
vestimenti, 3
Penis, 20
Peristalsis of gut, 16, 29
Perkins on typhus, 116, 117
Petrol, 62
Pharynx, 15
Phth'irus pubis, 3, 76
Pigs, human lice on, 2
Pit, Russian, 58
Plague, 2, 66, 68
Pomades, 73
Prevalence of lice, 3, 43, 112
Priestley, Major A. E., 115
Prison camps in Germany, 9, 134
Progression of body-louse, 37
of crab-louse, 78, 80
Protozoa, 101
Pubic hair, body-louse on, 70
crab-louse on, 79
head-louse, on, 70
Rat fleas, 2, 66
Rearing of body-lice, 32
of crab-lice, 78
of head-lice, 70
Rectum, 17
Reinfestation, 64, 65, 75, 82
Relapses of trench fever, 125
Relapsing fever, 9, 83, 99, 100
Repellants, 60
Reproduction of body-louse, 32
of crab-louse, 79
Reproductive organs, 16, 20
Respiratory system, 17
Rheumatism, trench fever resemb-
ling, 123, 124
Roumania, relapsing fever in, 107
typhus in, 116
Russian Army, typhus in, 114
Russian pit, 58
Salivary glands, 17
secretion of, 28
* causing fever, 83
Sanitary bins as disinfestors, 55
Scratching louse-bites, 7, 9
loosening hair, 81
infection, causing, 9
by relapsing fever, 105
by trench fever, 127
by typhus, 111
Scratching sticks, 4
Serbia, typhus in, 52, 116
Serbian barrel, 52
Sergent on relapsing fever, 104
Sex of lice, distinctions, 14
Shaving of body hair, 64, 82
Shin pain in trench fever, 123,
125
Sick, cleansing of, 112, 119
Skin, effects of lice on, 7, 80, 83
of louse, 25
Sleeping sickness, 66
Sleeplessness caused by lice, 9
Soap shortage and epidemics, 113
Soft soap, 62
Specialisation of lice, 2
Species of lice infesting man, 3
Spiracles, 18, 63
Spirochaetes, 101, 104
Spread. See Dissemination
Stabber, 15, 28
Stammers, Lt.-Col. G. F., 52
Starvation of lice, 37
Steam chambers, 55
Storage, disinfestation by, 46
Sucking lice, 2
Sulphur, 63
Superstitions concerning lice, 6, 57
Sutcliffe, Capt. A. C., 115
Sweat dissolving louse excreta, 31
dried, obscuring crab-lice, 78
Tabanidae. See Horse-flies
Temperature, disinfection of louse
excreta, 49
disinfestation, in, 48, 49, 53,
57
recording, 58
effect on development of louse,
29
incubation of egg, 23
starvation of louse, 37
louse-borne diseases, in, 99,
124
lysol solution, of, 61
Testes, 20
Tick. See Ornithodorus
Todd on relapsing fever, 103, 104
Tracheae, 17
Transmission of relapsing fever,
102
of trench fever, 127
of typhus, 111
136 LICE AND THEIR MENACE TO MAN
Trench fever, 9, 82, 84, 85, 120
virus in louse excreta, 49, 64,
127
Trenches associated with trench
fever, 120
Tropics, lice in, 43
Tsetse-flies contrasted with lice as
regards difficulty of control,
66
feeding habits, 2
Typhus, 9, 28, 52, 54, 83, 106,
108
in Roumania, 116
in Serbia, 52, 54, 116
Underclothing, disinfestation of.
See Disinfestation
lice reduced by changing, 4, 35
repellants on, 62
Vagabond's disease, 8
Vagina, 20 -
Vermijelli, 63
Vidal, Capt. A. C., 115
Virus of relapsing fever, 1O1
of trench fever, 122, 124, 128
of typhus, 110
Volhynia fever, 122
Wars causing increase of lice, 6, 35
epidemics of louse-borne dis-
ease, 106, 113, 116
Water, action on lice, 40, 48
Wells on typhus, 116, 117
Wet heat, damaging leather, 50
disinfestation by, 49, 57
Wind disseminating lice, 36
Wittenberg Camp, ~1 1 4
Yellow fever, 67
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