pediculosis corporis; an updating of attitudes - Phthiraptera

an Updating of Attitudes
J.W. Maunder, Department of Entomology.
London School of Hygiene & Tropical Medicine
INTRODUCTION
In advanced countries clothing lice are often perceived as being
more monstrous and disgusting than they really are. Parallel distortions
occur in the way in which vagrants (the usual hosts) are
seen, again being regarded with exaggerated disgust. In both
cases the underlying emotion is fear. This needs guarding against,
for, on the one hand, an unadmitted fear of vagrants and the
down-and-out may lead to unnecessarily harsh treatment of
them, while, on the other hand, a subconscious fear of lice may
lead to exaggerated or illogical control measures being employed.
In our society it is impossible to sustain clothing lice for more
than a few days unless a considerable departure from normally
accepted standards of hygiene and self-care has occurred. This
provides the clue to effective treatment, which must always aim
at the restoration of normal hygienic standards of life. The killing
of the insects is only an adjunct to the care of the individual carrying
them.
A Disease
The mere possession of clothing lice constitutes a disease,
pediculosis corporis, the infective agent being Pedj’cu.lus humanus
humanus, the human clothing louse. The course of the disease
maybe divided into three parts: an incubation period, followed
first by primary and later by secondary sensitisation. When the
body is first invaded by lice the process is quite symptomless,
unless an occasional tickle caused by a louse moving on the skin
may be classed as a symptom. Each louse feeds by sucking blood
from its host four or five times each day. The skin is pierced with
the long delicate mouthparts which normally lie hidden from
view in a housing running the length of the head. During the
incubation period the bites are quite painless, leave no mark and
cause no reaction.
However, into the bite wounds the lice inject a relatively large
volume of saliva. It is a mixture of blood and saliva which is
drawn up by the lice. This saliva contains an anti-coagulant to
prevent the blood from clotting in the insects’ own feeding tubes.
It also contains a red-cell clumping agent, various digestive
enzymes and, by analogy with other blood-sucking insects, probably
a local anaesthetic.
Also, as the insects increase in number, so does the total of bites
sustained. The presence of 200 lice in the clothing, a moderately
heavy infection, will result m approximately 1,000 bites each
day. Thus a significant quantity ofbiologically active protein will
be injected through the skin on a regular basis, day by day. It is
against this that the body eventually reacts,
Human beings vary very much in their response to sensitising
proteins. As few as 10,000 louse bites may be enough to induce
primary sensitisation in some individuals, others may require as
many as 100,000 bites. In general such levels are attained three to
eight months after the original infection with lice, when the
primary, local, sensitisalion develops.
From this point on, bitten areas begin to itch. This is usually
most uncomfortable; sleep is disturbed and scratching may lead
to secondary bacterial infection. (Following a cure, any subsequent
louse infection may begin to itch at once, for the primary
sensitisation is retained, resulting in an incubation period which
is shorter or absent).
The literature contains many instances of failure to appreciate
the importance of, or even the existance of, sensitisation
phenomena. For example, Moore and Hirschfelder, in 1919, correctly
described the results ofheavy louse biting, choosing as subjects
people who were used to being bitten. Buxton, in 1947,,
dismissed this evidence on the grounds that biting experienced by
himself and his associates caused little reaction. With the benefit
of hindsight we can be sure that the middle class volunteers concerned
had been insufficiently bitten on previous occasions to
have developed sensitivity. Individual variation is illustrated by
one of Buxton’s associates, now Professor J.R. Busvine, who
went on to feed very large numbers of lice on himself over many
years without developing more than a low degree of sensitisation.
On the other hand, I myself, and several associates, have become
so sensitised as a result of experimental louse feeding as to be able
to testify that to a sensitive individual even a few dozen bites a day
are a most unpleasant experience,
Worse is in store for the long-term lousy person. Secondary
sensitisation develops approximately twelve to eighteen months
after infection with lice. A general and systemic reaction now
occurs. The patient may run a slight temperature; muscular aches
and pains start, especially in the feet and legs; a short-lived rash
resembling German measles often forms; a dull and pessimistic
frame of mind develops, and the person becomes apathetic if left
alone and irritable if roused. Such a person is not well, in fact he
feels lousy, presumably the origin of the phrase. People do not
merely have lice, they also suffer from them.
Unfortunately much of the malaise of pediculosis is often
wrongly ascribed to mental deficiency, alcoholism, vitamin
deficiency or depression, although, of course, one or more of
these conditions may also be concurrently present,
Complications may yet occur. Prolonged heavy biting may
result in areas of skin becoming permanently hardened and
darkened, the condition known as morbus errorum. Some sufferers
become allergic to the faeces of the lice, developing a condition
similar to hay fever. (This is, in particular, a hazard of
laboratory workers handling lice.)
Difficulties attend the diagnosis of pediculosis. Many cases are
light, due either to short duration or to the anti-louse activities of
the host. The average infection involves rather less than 100
insects and these, grey in colour and preferring to secrete themselves
in seams of clothing, are easily missed, especially as they
are largely found in underclothing, which is, (or was.’), predominantly
white in colour.
Many persons with lice will make the effort to change’their
clothing, especially underwear, if a visit to the doctor is
necessary. Actual lice rarely appear in the surgery, but elongated
bitten areas on the body, often following the outline of the seams
of an undervest or other clothing, provide an indication of the presence
of lice. Emergency clinics see them much more frequently.
ACTION
When a lousy person undresses, or is undressed, the viable lice
will stay in the clothing rather than on him. Any insects dropping
out onto the floor, or remaining on the patient, are of little
significance. These are the senile, injured, sick or dead lice, or
else merely the cast skins shed by the insects as they grow. Lice
are only mortal, and their bodies must go somewhere!
Lousy clothing may be safely handled provided that a few
minimal precautions are taken. In bright light the insects will not
transfer to a new host, preferring to crouch motionless, often in
seams, attempting to escape detection. Care should be taken not
to allow the lousy clothing to touch the handler’s own. The special
tight-fitting protective clothing which used to be recommended is
not really necessary, nor is it very effective, although some form
of washable or disposable outer garment is obviously desirable
for other reasons. White is the best colour; lice will avoid making

themselves conspicuous.
Having separated the lousy person from his or her clothing the
problem is resolved into two parts: what to do with the person,
and what with the clothing. The first is a medical and social problem,
the second may now be thought of as environmental.
Treatment
The treatment of lousy people must not contain any punitive element.
Influenced by deep-seated fear of the parasites, kindly and
intelligent people can act in surprisingly irrational and even cruel
fashion towards the lousy, without being properly aware or’thew
own motivation. The old, grim Victorian disinfestation centres,
staffed by unqualified attendants, acting more as warders than as
nurses, lingered on too long; nor were they altogether effective.
for suchwas the humiliation involved that lousy people often preferred
to keep their lice as long as possible.
Strangely, few destitute people see themselves as tramps or
vagrants. In their own eyes they are simply suffering a period of
bad’luck. They may retain more human dignity and self respect
than is externally visible, and these need fostering and supporting.Punitive
measures are inappropriate.
Clinics treating pediculosis corporis should ideally be part of
larger multi-professional medical centres where the advice of
doctors, social workers and even chiropodists or dentists is
immediately available. Lousiness may be the presenting symptom,
but it is unlikely to be the sole one. Delousing is only a starting
point, not an end.
Clinics should be in the charge of a person suitably qualified for
the recognition and treatment of the various ectoparasitic diseases
and with sufficient medical knowledge to recognise when a
doctor’s advice is needed, A senior qualified nurse, male or
female as appropriate, is the most likely choice, but other
qualifications are possible. The appointment of other staff needs
great care. Patience and good humour are essential, combined
with the ability to be firm as necessary, but the types of firmness
displayed by policemen, army sergeants and prison officers,
however praiseworthy in their own contexts, are quite unacceptable
in this situation. Rather, the brisk no-nonsense kindliness of
a good schoolmaster is needed.
Staff at all levels cannot be expected to perform their duties
without training. Close supervision is also needed; experience
has shown that this is an area where harshness, hectoring and
even bullying can insidiously invade what ought to be a caring
service.
The clinic premises should be sufficientlywarm. People suffering
from poor nutrition feel the cold more intensely. Washable
cork or composition floors, warm to the touch, must be provided
and chairs and benches should also not feel cold,
Adequate attention must be paid to the privacy and dignity of
the patients. Cubicles or screens of some kind are needed, for noone
should be expected to undress with other patients watching.
Washable or disposable gowns need to be provided for each person.
The former humiliating practice of leaving patients standing.
naked while their clothing was dealt with was a cruelty which
must never be allowed today.
The bath is an optional extra. Patients have an absolute right to
refuse it, and staff training must emphasise that lousiness and dirtiness
are two separate problems. Both may be symptoms of
neglect, but they are not otherwise related. Taking a bath as such
does nothing to cure lice and therefore is not part of the treatment.
Nevertheless, it should be encouraged as a service, as an agreeable
thing to do, and because to be clean helps self respect. (A
ENVIRONMENTAL HEALTH MAY 1983
compulsory bath does not aid self respect; rather the opposite.)
There is a world of difference between making someone do a good
thing and encouraging them to do it for themselves,
It is unlikely that any viable clothing lice will remain on the
body after undressing, but other conditionsmay be present. A few
clothing louse eggs are occasionally found on body hair, but most
of such claims are really due to confusion with the eggs ofthe crab
louse. The body hair of both sexes and the beards and head hair of
men may contain crab lice and their eggs. The practice of clipping
body hair is quite unnecessary. The head hair ofwomen may contain
head lice, but this louse is rare on the heads of adult men.
Scabies may be present in either sex.
Diagnosis and treatment of all these conditions cannot be left to
unqualified or untrained staff. In general, insecticidal lotions are
to be preferred to powders, which have an insufficiently intimate
contact with louse eggs, or to shampoos, which are left on too
short a time to be fully effective. If only clothing lice are present,
insecticides are generally superfluous; nothing is more important
than the restoration of regular changes of clothing.
Social Workers
Social workers involved with pediculosis corporis should be
aware that although clothing lice are associated with abject
poverty and with vagrants and refugees, this is not because they
are poor or dirty or homeless as such, but because they are using
only one set of clothing. Anyone who possesses only one set of
clothes, or, owning more, does not change, runs the risk of
pediculosis. If two sets of clothing are in rapid alternate use, then
two sets of lice can be kept. However, anyone who changes between
two sets of clothing regularly, never keeping one set on for
more than twelve days or for less than five, cannot keep lice no
matter how dirty or otherwise unhygienic he may be. It has been
suggested that this is the origin of the week,
The first aim of the social worker, then, must be to ensure that
patients newly cured of lice possess two sets of clothing. Then, if
possible, provision needs to be made for, and the patient
encouraged to make, regular changes of clothes. This usually
implies provision of some kind of home, but this may be difficult.
Our society does not do enough for the single homeless
person.
If the lousy person is also otherwise ill, special care may be
needed in his treatment. This is particularly true of those who are
brought to casualty and emergency clinics following accidents or
sudden illness. The presence of lice in such a person’s clothing
can sometimes induce a literal panic in those who.discover them.
Many a good nurse, who would devotedly tend persons suffering
from dangerous infectious illness, cannot bring herselfto as much
as touch the lousy. If a seriously entomophobic person is in
charge, the patient may be in actual danger. Cases are recorded of
hospital staff dressing themselves up in protective clothing, donning
rubber gloves and thoroughly scrubbing the patient with
soap, disinfectants, benzyl benzoate and powerful insecticides,
regardless of what other medical condition he may be in. All too
often the result is a very sweet smelling but very dead tramp, for
many of these people are in no fit state to stand such treatment.
Better that a vagrant with, say, a coronary, should keep both his
lice and his life until he is fit enough for gentle removal of his
clothing and forwashing. It is not in the patient’s best interest that
we should be afraid of him for no other reason than that he is a
tramp, nor that we should over-react to his lousiness.
Infested clothing
The treatment of infested clothing needs Just as much care and

sensitivity as does the treatment of infected people. An overcoat
which wouldbe thrown away at once by the average person might
well be a vagrant’s single most treasured possession. If it comes
back from some steam disinfestor shrunken and unwearable then
a first class disaster will have occurred in that man’s life.
If lousy clothing is washed, all that is achieved is cleaner lice
unless the water is hot enough to kill the lice. As a general guide, if
the water is too hot for the hands to be put into it then the lice will
be killed. If the water is cool enough for hand washing then they
will survive. The disadvantages of delousing by hot-water washing
are that the process is very slow and somewhat expensive, and
also that many items of clothing, especially outer-wear, cannot be
satisfactorily washed. The advantage is that clothing is returned
very clean.
The old-fashioned steam steriliser is on its way out, if for no
other reason than excessive cost. Heat penetrates a static pile of
clothing very poorly, and alternated applications of steam and
vacuum are needed. The vast size of some of these old pieces of
equipment gives a false impression of effectiveness. In fact,
unless the operation is carried out most carefully, louse eggs will
survive, for they are protected from excessive temperatures by
being hidden in seams. Apart from expense, the disadvantages
include damage to clothing, especially buttons, zips and other
plastic components, slowness of operation and the fact that the
clothes are returned still dirty. Steam sterilisation has little to
recommend it.
Dry-cleaning of clothes is effective against both lice and eggs,
On a large scale it becomes more economically justifiable. The
disadvantages are the comparatively high expense and the fact
that the clothes must be very well aired before return, which
slows the process down. The advantages are that clothes are
returned clean and that outer clothing can be safely treated. The
extra expense can often’-be justified in terms of human happiness
and the encouragement to self respect, for a dry-cleaned overcoat
does much to raise morale. If it were more widely known that drycleaning
fluids are completely effective insecticides against
clothing lice, then the process might be employed more widely for
this purpose.
The use of fumigants, for example methyl bromide or ethyl formate,
if done properly, is as effective for killing lice as drycleaning.
The cost is less, but the clothing remains dirty, the
treatment time is prolonged (several hours are needed), and an airing
period is still needed. Ethyl formate is the most effective compound,
but constitutes a fire hazard. Well ventilated and
electrically safe areas are needed for its employment. Ethyl formate
can damage plastic components of clothing, especially ifthe
liquid compound, instead of only the vapour, comes into contact
with them.
Methyl bromide is effective, not a fire hazard, is less damaging
to clothing and needs less airing, but is so toxic to man that very
careful training and supervision must accompany its use. In particular
the risk of accidental poisoning is high, for there are few
warning signs or symptoms. At low temperatures, less than 10C,
fumigation loses much of its effectiveness.
The newest development in the treatment of lousy clothing has
been the introduction of dry tumble-drying, following a description
by Maunder in 1977. Clothing is placed dry in a normal
domestic or industrial tumble-dryer. Because dry clothing does
not cool itself by evaporation of water, a temperature lethal to the
louse is soon attained throughout the whole of the clothing. The
old problems of poor heat penetration which placed such severe
limitations on the efficiency of hot air ovens and steam disinfectors
are totally overcome.
The temperatures necessary to kill lice are remarkably low
once a method has been found to bring the heat to the insects.
Buxton, 1940, gives the following minimum lethal temperatures:
It is also known that even lower temperatures are effective if
the humidity is low, as, of course, it would be in a dry tumbledryer.
In practice it has been found that if a suitable machine is set to
give a final exhaust temperature in excess of 60C, then even a
domestic tumble dryer will kill all lice and eggs inside fifteen
minutes when the machine is started from cold. Before installing
a machine for this purpose it is as well to check with the manufacturers
as to the suitability of any model.
For clinic use it is best for the exhaust from the machine to be
channelled to the outside, for the dust from lousy clothing can be
irritating if breathed in, and such dust will not be sterile. Any
dangers from this dust are no greater than from shaking lousy
clothing in a room, but if aesthetically and hygienically undesirable
for exhaust air to be vented indoors..
The dry tumble-drying method has the advantages of low capital
outlay, rapid turn-over of small batches of garments, little risk
of damaging clothing and high effectiveness. The clothing is
returned dirty, but after this treatment it is safe to send it for conventional
laundering if desired.
CONCLUSION
Pediculosis corporis is a disease, not as serious as the major louseassociated
diseases such as typhus and relapsing fever, but a disease
nevertheless. Our updated attitudes call upon us to treat the
condition as we would any other, not fastening moral blame onto
the sufferers to carry in addition to their lice and their concommitant
problems. The lousy have enough to bear, and they are only
human too.
Our fear of lice is largely quite illogical. Often if helps to stop
and look at a live louse for a while. The monster is then cut down
to size, and becomes just another little insect.
References
Buxton, P.A. (1940]. The biology of the body louse underexperimental
conditions. ParasitoJogy, 32, 303-312
Buxton, P.A. (1947). The Louse. 2nd Ed. Edward Arnold
(London].
Maunder, J.W. [1977). Human lice biology and control. Royal
Society of Health Journal, 97, 29.
Moore, W. and Hirschfelder, A.D. (1919). An investigation of the
louse problem. Research Publications of the University of Minnesota,
8, 1-86.