St Aiden's Health ~ Head Lice Information

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HEAD LICE INFORMATION

statement from Richard J. Pollack, PhD

Head lice: Information and Frequently Asked Questions

Infestations by head lice become most apparent at the beginning of each school
year. Parents, day care providers, school officials and healthcare professionals
frequently seek information and solutions to this burdensome problem.
Accordingly, we have provided answers to frequently asked questions concerning
this subject. We hope this information will be useful.

• What are head lice, and how do they differ from other lice?

o Body lice

o Pubic or crab lice

o Book, bark lice, beggar's and sea "lice"

•        Cryptic infestations
•        Do head lice cause harm?
•        Why were my children sent home from school (the 'No Nits' policies)?
•        From whom did my child acquire head lice?
•        What is the origin of head lice?
•        How many people are infested by head lice?
•        What methods can I use to treat the infestation?

o Should everyone in the home be treated?

o Are lice resistant to insecticides?

o Do insecticides cause resistance?

o Mechanical removal

o Pyrethroid insecticides

o Non-pyrethroid insecticides

 Malathion
 Lindane

o Essential oils

o Enzyme treatments

o Suffocating agents

o Antibiotics

o Antiparasitic drugs

o Heat

o Freezing

o Haircuts

o Hair soaps, bleaches and dyes

o Do dogs and cats serve to maintain or transfer head lice?

o Should I clean my house or car?

o What should be cleaned?

o Should I use insecticides in the house to rid it of lice?

o Can anything be used to repel lice?

•        How can I have specimens evaluated?
•        How to document an infestation
•        NEW Images of lice and eggs
•        NEW Management schemes

What are head lice, and how do they differ from other lice?

Head lice (Pediculus capitis) are small parasitic insects exquisitely adapted to
living mainly on the scalp and neck hairs of their human host. Their six impressive
legs are elegantly evolved to grasp hair shafts and provide a striking example of
biological specialization. Long associated with people, head lice have been
recovered from prehistoric mummies. Head lice are equal opportunity parasites;
they do not respect socio-economic class distinctions.

Their presence does not connote a lack of hygiene or sanitation practiced by their
host. Head lice are mainly acquired by direct head-to-head contact with an
infested person's hair, but may infrequently be transferred with shared combs, hats
and other hair accessories.

They may also remain on bedding or upholstered furniture for a brief period.

In North America and Europe, children are more frequently infested than are
adults, and Caucasians more frequently than other ethnic groups. Neither able to
fly nor jump, lice are also unlikely to wander far from their preferred habitat.

Lice and their eggs are unable to burrow into the scalp. Lice are sometimes
referred to as cooties, eggs as nits and infested people as lousy.

The infestation by head or body lice is termed pediculiasis, and the associated
"disease" pediculosis. Delousing (more properly termed lousing) consists of any
method for eliminating an infestation. Chemical treatments directed against lice
are pediculicides. Those that kill adult and nymphal lice are sometimes called
lousicides; those that kill the developing embryo within the egg are ovicides. This
discussion relates to head lice unless specific mention is made of other types of
lice.

Head lice derive nutrient by blood-feeding once or more often each day, and
cannot survive for more than a day or so at room temperature without ready
access to a person's blood. A nymphal louse hatches from its egg after about 8
days of development, and begins to feed, grow and develop until it attains the
adult stage about 9-12 days after hatching. A female louse may deposit more than
100 eggs at a rate of about six eggs each day. Only those eggs deposited by
inseminated female lice will hatch. Generally, an infested person has fewer than a
dozen active lice on the scalp at any time, but may have hundreds of viable,
dead and hatched eggs. With adequate magnification, the developing nymph
can be seen within the egg; hatched eggs are nearly transparent.

Treatment should be considered only when active lice or viable eggs are
observed.   Itching of the scalp or the perception that something is crawling on
the head do not warrant treatment for lice. Without magnification and suitable
experience, they may be difficult to correctly distinguish from other material
caught in the hair.

Amongst presumed "lice" and "nits" submitted by physicians, nurses, teachers and
parents, most are simply artifacts such as dandruff, hairspray droplets, scabs, dirt,
or other insects (e.g. aphids blown by the wind and caught in the hair). To confirm
the identity of suspected material, save a few lice and louse eggs under clear
tape on our specimen submission form, and record the requested information.
Submit the samples to us or to a qualified physician or entomologist to confirm the
identity of the offending creatures .

Body lice (Pediculus humanus) are closely related to head lice, but are less
frequently encountered in the US. As the name implies, body lice generally feed on
the body, but may rarely be discovered on the scalp and facial hair. They usually
remain on clothing near the skin, and generally deposit their eggs on or near the
seams of garments. Body lice are acquired mainly through direct contact with an
infested person or their clothing and bedding, and are most commonly found on
individuals who infrequently change or wash their clothes. A change to clean
clothes, and laundering of infested garments (especially drying with high heat or
ironing), are generally effective to eliminate this burden.

Body lice (but not head lice or pubic lice) serve as vectors of certain human
pathogens. Epidemics of louse-borne typhus, louse-borne relapsing fever and
trench fever decimated the populace through the ages, and millions more
perished from these infections during the 1900's during major conflicts and
famines. Fear of these diseases fueled atrocious and perverse campaigns to
quarantine and assault unpopular ethnic groups suspected of promoting risk.
Current efforts to seek out and quarantine individuals infested with head lice may
be driven, in part, by those who misinterpret or intentionally misapply certain
principals of public health.

Pubic or crab lice (Pthirus pubis) have a short crab-like body easily distinguished
from that of head and body lice. Pubic lice are most frequently found around the
pubic region of the infested person, but may also be found elsewhere on the body
(including facial hair and eyelashes). The infestation by pubic lice is termed
pthiriasis.

Mechanical removal of these lice and their eggs is the preferred method of
treatment. Because pubic lice are acquired mainly through sexual contact, their
presence may be associated with other sexually-transmitted diseases. Pubic lice
on a child may cause the physician to consider the possibility that the child may
have had inappropriate contact. Pubic lice may also be acquired through more
innocent means, such as by sharing a bed with an infested person.

Book, bark, beggar's and sea 'lice' are quite unrelated to human biting lice. Book
and bark lice are insects commonly found in organic material such as leaf litter,
under bark of trees, and even within the pages of books. Book lice, when
abundant, can cause damage to books and are considered pests in library
collections. Book and bark lice are occasionally submitted for identification as
presumed parasites. Their presence on a person's body is merely incidental; they
do not parasitize people. Diverse types of plant seeds adhere to clothing and hair,
and are commonly termed "beggar's lice." Some insects related to aphids are
known as "plant lice." Certain parasites of fish are known as 'sea lice", but this term
is often misapplied to a condition known as 'seabathers' eruption" that seasonally
affects bathers along the seacoasts (apparently due to contact with stinging cells
of certain jellyfish). Finally, although diverse types of lice parasitize mammals and
birds, these rarely affect people.

Cryptic infestations

Some people earnestly believe that they are actively infested, even though no
louse or other parasite can be detected. These cases can be particularly difficult
to manage, and the affected individual should not be dismissed as being unstable.
Every reasonable effort should be explored to identify the cause of the irritation
and to capture and identify any offending creature on the scalp or body. The
irritant may, indeed, be a louse or some other type of biting insect or mite, but may
not necessarily be infesting the person at the time of examination.

Diverse insects (e.g. mosquitoes, fleas, bedbugs) may only transiently visit a
person, and may or may not be noticed in the act of biting. Certain mites
associated with bird nests occasionally wander into a house and cause
annoyance. Itching and irritation in some cases may also be ascribed to hair care
and laundry products, industrial fibers, underlying disease, or even to the
pediculicidal (anti-louse) treatment. The clinician will often find it valuable to
consult with an entomologist on these matters

A few people remain convinced that their infestation is real, even though they
have been examined by one or more competent specialists who can find no
physical cause for their discomfort. Some of these patients may pose a danger to
themselves and others by resorting to the use of toxic or flammable substances in
attempts to rid themselves of their real or perceived infestation. Such a person
may, indeed, be delusional, and should be treated with care and respect when
referred for counseling. Certain people develop an extreme phobia or irrational
fear that they will acquire lice or other parasites from virtually any animate or
inanimate object. Patients that are unduly burdened by this condition are likely to
benefit from counseling with a clinician specializing in phobias and obsessive-
compulsive disorders.

Do head lice cause harm?

Head lice rarely (if ever) cause direct harm, and they are not known to transmit
infectious agents from person-to-person. Thus, they should not be considered as a
medical or a public health problem. These lice may occasionally be burdensome
because of annoyance; their presence may cause itching and loss of sleep. The
louse's saliva and feces may sensitize people to their bites, thereby exacerbating
the irritation and increasing the chance of secondary infection from excessive
scratching.

The greatest harm associated with head lice results from the well-intentioned but
misguided use of caustic or toxic substances to eliminate the lice. A few lice on
the head should not cause alarm; rather, they present an opportunity for parents
to spend the needed time with their children in order to find and remove the
offending insects. Grooming can be an effective method to remove lice, and
engenders several associated physiological and behavioral benefits as well.
Because of unfounded fears, some parents have suggested that children refrain
from sharing protective batting or biking helmets. The miniscule risk of acquiring
lice from such devices pales in comparison to the hazards averted by helmets.

Why were my children sent home from school (the No Nits policies)? The no-nits
policies variously drafted and adopted by school administrations aim to reduce
the transmission of lice by excluding infested children from school. Whereas these
policies are meritorious in principle, they are virtually always counterproductive
when applied. School nurses are generally amongst the most capable to spot
signs of infestation, but lack the expertise and equipment to distinguish active
from inactive infestations. School personnel and parent volunteers often conduct
mass-screenings in misguided and failed attempts to identify infested children and
ensure their treatment. Concerned parents, nurses and school administrators may
find it valuable to cooperate by drafting rational policies. The discovery of lice or
their eggs on the hair should not cause the child to be sent home or isolated.

Furthermore, treatment is not indicated if the infestation is not active.

Although lice and their eggs may be seen without the help of magnifying devices,
the viability of the eggs cannot be judged without magnification and a degree of
training. Of more than six hundred samples of presumed lice and nits submitted to
us for examination, fewer than two-thirds contained evidence of any infestation.
The remainder of the samples were composed of miscellaneous insects or of
artifacts that resembled eggs. Of those samples that did contain bona-fide louse
eggs, many were comprised solely of hatched or dead eggs; thus, no treatment
would be warranted.

We noted that:
1.        health care professionals as well as non-specialists frequently over-diagnose
this infestation,
2.        non-infested children are quarantined as often as infested children,
3.        traditional pediculicides and alternative formulations are frequently over-
applied

Because pediculiasis is generally misdiagnosed, and because few symptoms and
no direct infectious processes are know to result from an infestation, we suggest
that the practice of excluding presumably infested children from school is
unwarranted.

The full citation of our published article is:

Pollack RJ, Kiszewski A, Spielman A. Overdiagnosis and consequent
mismanagement of head louse infestations in North America. Pediatric Infectious
Disease Journal. 2000; 19:689-693.
The abstract and article may be accessed through the Journals web site: http:
//www.pidj.com/
Although head lice are transmissible, their potential for epidemic spread is
minimal. Indeed, the basic reproduction number (a measure that defines the
number of secondary infections arising from an index case) would be far lower for
head lice than for infections due to cold or flu viruses - yet children are rarely
excluded from school because of these often more-debilitating infections.
Furthermore, we are unaware of any convincing data that demonstrates that
enforced exclusion policies are effective in reducing the transmission of lice.
These quarantine policies seem a disagreeable vestige of certain offensive and
supposedly health-based anti-ethnic strategies practiced mainly in Europe earlier
this century. It is our professional opinion that the no-nits policies are imprudent, as
they are based on intolerance, hysteria and misinformation rather than on
objective science.

Lice on children's heads, by themselves, should not be cause for the schools or
courts to brand the parents as 'neglectful' or 'abusive'. We are aware of several
cases where the courts have ordered children removed from the custody of their
parents because of their apparent failure to eliminate the infestations. Such
extreme actions to an infestation are generally unwarranted and may suggest
poor judgment on the part of those making policy decisions. We are also aware of
legal actions brought against the schools by the parents of children who have
been excluded from school.

These actions should now prompt school administrators to reevaluate their
practices of identifying infestations as well as their exclusion policies and
treatment recommendations. We encourage parents and school administrators
affected by these policies to send us details of their cases.
From whom did my child acquire head lice? Head lice are acquired from other
infested people. Upon learning of their child's infestation, parents frequently seek
to ascribe blame. This 'knee-jerk' reaction is understandable but unproductive. The
offending lice came from some other person, but it is not currently possible to
determine the identity of the donor. Parents are encouraged to focus their
energies on education and treatment rather than on unsuccessful witch-hunts.
Rather than accusing the school administrators or other parents for not preventing
spread of head lice, parents are likely to benefit more by ensuring all children and
adults in the home are inspected and treated as appropriate.

What is the origin of head lice? Human lice likely co-evolved with people. Our
primate relatives harbor their own species of lice. Lice are quite host specific;
human lice, for instance, will not feed upon other animals, and lice of other
animals would rarely feed upon a person.

How many people are infested by head lice? Few useful statistics are available
for estimating the prevalence of infestation. Far fewer people seemed infested
than the general public or the medical community might believe. Reports of
"epidemics" of head lice may generally be attributed to incorrect identifications
and misdiagnoses. The apparent annual and seasonal "increases" in prevalence
may be real or due to peculiarities in monitoring activities. The perception that
lice are more prevalent today then in past decades may, perhaps, reflect societal
changes in candor in discussing such issues

What methods can I use to treat the infestation? First, ensure that a correct
diagnosis/identification has been made before considering treatment options. An
old infestation, manifested solely by hatched eggs, is not a cause for treatment.
Treatment should be considered only when active lice or viable eggs are
observed (refer to the images of lice and eggs). Several options exist to eliminate
the infestation, but some are better tested than others. Success will likely depend
on an integrated approach that relies on several of the methods listed below,
combined with perseverance and a bit of levity. Because the egg is particularly
resistant to some chemical treatments, a second treatment is often required
about 10 days later to target the nymphs that hatch after the initial treatment.
We have drafted management schemes to assist the parent and school
administrator.

a) Misdiagnosis (no active infestation, or misidentification),
b) Non-compliance (not following treatment protocol)
c) Resistance by lice to the insecticide
d) New infestation (lice acquired after treatment)
e) Lack of ovicidal (egg-killing) or residual properties of the product.

Reports of resistance or lack of sensitivity to insecticides by head lice in other
countries have been published in the scientific literature, and non-peer-reviewed
reports abound elsewhere.

Accordingly, we investigated whether head lice in the US had developed
resistance or tolerance to pyrethroid insecticides. We developed a bioassay to
test the responses of lice to permethrin, and identified infested children who could
provide us with the needed samples.

Our findings were published in a peer-reviewed medical journal. In brief, we
reported that:

1) head louse infestations in the US are surprisingly infrequent,

2) head lice sampled from children who were chronically-infested and treated
multiple times with pyrethroid shampoos tend to be resistant to permethrin,

3) head lice sampled from children living where pyrethroids are rarely used against
lice (Malaysian Borneo) tend to be susceptible to permethrin,

4) lice that are resistant to permethrin at low doses are generally resistant to high
doses as well; thus prescription formulations of containing permethrin at
concentrations of 3-5% are unwarranted,

5) the prevalence of resistance to permethrin has yet to be determined. This final
point is of critical importance in understanding the significance of our findings. In
our report we document the existence of permethrin-resistant head lice in the
United States. This should not be interpreted as meaning that all (or even most)
head lice are resistant to permethrin and related compounds.

Permethrin and pyrethrins remain the treatment of choice for newly-identified
infestations. If live lice persist following such treatments, then one may consider
that these lice may be resistant to this family of insecticides. Further treatment
may be warranted with pediculicides containing other insecticides.

The full citation of our published article is:
Pollack RJ, Kiszewski A, Armstrong P, Hahn C, Wolfe N, Rahman HA, Laserson K,
Telford SR III, Spielman A. Differential Permethrin Susceptibility of Head Lice
Sampled in the United States and Borneo. Archives of Pediatrics and Adolescent
Medicine. 1999;153:969-973
The full article can be viewed on the American Medical Association's web site:
http://archpedi.ama-assn.org/issues/v153n9/toc.html

Do insecticides cause resistance? Insecticides generally do not cause mutations
leading to insecticidal resistance. Rather, any insect (or any organism) may, by
chance, have the capacity to avoid, detoxify or eliminate toxins from its body.
These few individuals may survive treatment, reproduce and serve to establish a
larger population of lice that are less susceptible to that insecticide and perhaps
to related compounds.

Mechanical removal Mechanically removing lice and nits can be an effective
but time-consuming method. Because most eggs will be non-viable, their removal
is often impractical and unjustified. An infestation may be eliminated by combing
each day to remove the live lice (including those that have hatched since the
previous day). Comb daily until no live lice are discovered for about two weeks.
Use illumination, magnification and a good louse or nit comb to locate and
remove the offending insects. Although the hair may appear 'peppered' with eggs,
there generally are fewer than a dozen active lice on the head at any time. Adult
female lice usually cement each egg to the base of a hair shaft near the skin. As
the hair grows (from the base), these attached eggs are transported away from
the scalp. Eggs more than one-half of one inch away from the scalp are nearly
always hatched and do not, by themselves, indicate an active infestation.

Louse or nit combs can be useful in removing lice and eggs. Diverse types of fine-
toothed combs may be included within packages of pediculicides or they may be
purchased from virtually any drug store, pet supply store (often at a discount) or
via the web. Some louse combs are better than others; their effectiveness
depends on

a) their composition (metal vs. plastic) and construction (length and spacing of
the comb teeth),

b) the texture of the hair to be combed,

c) the technique used to comb, and

d) the time and care expended in the effort.

Whereas straight hair is usually readily combed, tight curls may present an
impossible and impractical challenge. Hair should be cleaned and well-combed
or brushed to remove tangles before attempting to use a louse comb. Clean the
louse comb frequently to remove any caught lice or eggs.

It may require several hours each night for several nights to tackle the problem.
An entertaining video may help keep the child occupied during this exercise. Sit
behind the child, and use a suitably bright light (and magnification if available), to
inspect and comb through the hair, one small section at a time. Repeat until no
more active lice are observed.

Some parents report that water, vegetable oils or hair conditioners help lubricate
the hair and ease the combing process; others report that these lubricants make it
more difficult to see the eggs.
"Electronic" louse combs that resemble small bug "zappers", or those with
oscillating teeth would seem to offer little advantage, if any, over a well-designed
traditional louse comb. Teeth of these devices may not effectively reach to the
scalp and may not kill or remove eggs.

Pyrethroid insecticides Infestations may be treated with shampoos containing
permethrin or pyrethrins specifically labeled for use on people. Some formulations
also contain a synergist, a chemical that may enhance the activity of the
insecticide. As with any insecticide or drug, read and follow the label directions.
Because these products seem to have limited ovicidal (egg-killing) activity, a
second treatment is often necessary about 10 days later to target lice that hatch
after the initial treatment. Susceptible lice do not fall from the hair or die
immediately upon treatment with pyrethroids; one should wait until the next
morning to determine the fate of treated lice. As is true of any pediculicide,
pyrethroids do not remove the eggs from the hair.

Some physicians treat apparently resistant infestations with a prescription-
strength pyrethroid (3 - 5%) preparation normally meant for treating scabies
infestations. In our recently published article we report that some head lice in the
United States are resistant to permethrin, and that higher doses of this insecticide
generally were not more effective. Thus, prescription-strength pyrethroids are not
likely to be effective. Although permethrin and pyrethrins differ in chemical
structure, their mode of action is quite similar. Thus, we would anticipate that
pyrethrins would also be ineffective in killing permethrin-resistant lice.

Non-pyrethroid insecticides Other insecticides should be avoided unless
specifically prescribed by a physician. The organochlorine insecticide lindane, and
the organophosphate insecticide malathion are two of the active agents within
pediculicides available by prescription. The current susceptibility of these insects
to lindane or malathion has not yet been analyzed in the United States.
Prescription preparations containing these insecticides may be considered as
alternative pediculicides if live lice persist after two treatments with pyrethroid-
based pediculicides. Refer to our management flowcharts.

Use caution when dealing with any insecticidal agent, particularly on children.
Read and follow label directions. Do not apply any insecticide or other chemical
not specifically labeled for use on people.

Well-intentioned parents treating their children with toxic or flammable
substances have caused several deaths and poisonings.

Essential oils Numerous "home recipes" and commercial preparations are based
on mixtures of essential oils, salts or other "natural" substances. Data is lacking to
support the claims of their efficacy. Several formulations include substances that
should not be used on the skin, and may not be registered for such use by
government regulatory agencies (such as EPA or FDA).

Enzyme treatments The chemical structure of the "cement" that binds the egg to
the hair is not well-defined. Nonetheless, it is an exceptionally stable substance
that resists degradation by diverse chemicals. Several commercial products are
advertised to "dissolve" the eggs or the cement by which the eggs are attached
to the hair. We are not convinced of the effectiveness or safety of these products.

Antibiotics The guts of human lice contain a specialized organ that harbors an
unusual type of bacteria. These bacteria may aid the louse in digesting the blood
meal or by providing essential nutrients. Certain antibiotics may affect or
eliminate these bacteria from the louse's gut, and body lice that have fed upon
antibiotic-laden blood of people may be burdened and die. The effect of
antibiotics on the health of head lice has yet to be determined conclusively.
Physicians increasingly seem to prescribe combinations of the antibiotic agents
trimethoprim and sulfamethoxazole (e.g. "Bactrim", 'septra") in attempts to treat
head lice. We oppose this practice because these antibiotics are not approved
as pediculicides, and they are valuable in fighting life-threatening infections. Their
use for treating such a relatively innocuous condition as a louse infestation may
accelerate the emergence or spread of bacterial resistance, thereby diminishing
the usefulness of these antibiotics.

Antiparasitic drugs Diverse antiparasitic agents have been proposed for treating
human lice, but none has been evaluated critically. The drug ivermectin, for
example, is widely used in veterinary medicine as an antiparasitic agent, and is
available for human use for treating infestations caused by certain worms; it is not
approved for use against human lice. Accordingly, we suggest that such
treatments be avoided.

Suffocating agents An increasingly popular "alternative" treatment involves the
use of food-grade oils or hair gels in attempts to smother lice on the scalp. Many
people have provided anecdotal reports of their successes with this old method,
but we have also heard of nearly an equal number of failures. Virtually no data,
however, is available to assess the efficacy of this technique. As with any hair
conditioner, oils may lubricate and ease efforts to pass louse or nit combs through
the hair. Olive oil (or any similar food-grade product) would seem intrinsically safe,
but may have associated hazards, nonetheless. Oil may cause accidents (slips),
and would be difficult to remove from the hair and scalp (detergents can cause
irritation). Do not use motor or machine oils, as these materials can be harmful.

As a preliminary test to measure the effect of such agents on lice, we submerged
six active lice in olive oil, and maintained an equal number of non-treated lice in a
separate container. Lice removed from oil after one hour recovered, but those
submerged for two hours succumbed. Non-treated lice survived for at least 18
hours. We have not repeated this test on active lice nor have we tested this
treatment on nits. The results are simply of a very preliminary nature and should
not be construed as solid evidence on which one would base treatment
recommendations. It would be an error to extrapolate from data of such an
informal test; therefore, we do not recommend the use of olive oil (or other such
substances) as a treatment for head lice.

Heat The hot dry air produced by standard hand-held hair dryers may suffice to kill
lice and their eggs on a person's hair. Use great care if you try this method, as the
heated air from these devices can also easily scald the hair and the scalp. No
precise values (treatment time, temperature, and distance from hair dryer) are
available with which to base an objective treatment protocol. Heated curling
irons, hair straighteners or similar devices may kill some lice and eggs, but may not
safely be applied to hair nearest the skin where viable eggs are most abundant. A
clothes dryer set a high heat or a hot pressing iron may effectively kill any lice or
their eggs on pillowcases, sheets, nightclothes, towels and similar items that will
not be damaged by this process. Combs, brushes, hats and other hair accessories
in contact with an infested person should be washed in hot water each day to
dislodge any lice or nits.

Freezing Lice and their eggs on inanimate objects (e.g. toys) may be killed by
freezing temperatures. Objects that cannot be heated in a clothes dryer may be
placed in a freezer (or outdoors if sufficiently cold). This treatment may require
several days to be effective, depending on the temperature and humidity. Such
treatment would rarely (if ever) be required.

Haircuts Lice will find little to grasp on a bald or shaved head. Although
competitive swimmers who shave their heads generally need not be concerned
about head lice, many parents may find this old-fashioned method to be
aesthetically unappealing. Short hair is more readily searched for lice and eggs,
but does not make the child invulnerable to infestation.

All three types of human lice may occasionally be found on the eyelashes or other
facial hair. These lice should be mechanically removed with great care so as not
to injure the eye; insecticides should be kept well clear of the eyes as well.
Cosmetology practices and regulations often dictate that infested individuals be
sent away by the barber or beautician, and any implements that contacted that
person be properly cleansed.

Hair soaps, bleaches and dyes Washing the hair each day may dislodge a few
active lice; the remaining lice and eggs will be unaffected (but clean). Although
hair bleaches and dyes are meant for use on the scalp, they can be caustic. Data
is lacking to assess the efficacy of these products against lice. Thus, use of these
products in attempts to "treat" lice should probably not be considered. Assertions
that dandruff shampoos are effective in removing lice are probably due to
misidentification of dandruff as lice.

Do dogs and cats serve to maintain or transfer head lice? Pets are of no
significance in maintaining or transmitting human lice, and should not be treated
for head lice.

Should I clean my house or car? Head lice and their eggs soon perish if separated
from their human host. Removed lice survive just a day or so, and the eggs
generally lose viability within a week. The chances of a live head louse or egg
becoming reunited with a person would seem remote exceptionally.
Accordingly, Herculean steps to clean lice from the house or car by intensive
washing or vacuuming will result in a cleaner space, but are unlikely to significantly
facilitate the goal of eliminating the lice from those residing in the home. A child's
car seat cover may benefit from vacuuming, as a few errant lice or eggs may
temporarily lodge there and survive for a day or so.

What should be cleaned? Washing and drying (with heat) the pillowcases, sheets,
nightclothes, towels and stuffed animals may possibly eliminate lice and eggs that
might otherwise reinfest a family member. Combs, brushes, hats and other hair
accessories in contact with an infested person should be washed in hot water
each day to dislodge any lice and nits. Shared helmets and headphones in schools
or recreational settings may rarely and transiently harbor an occasional louse or
nit; the effort necessary to effectively inspect and clean these devices, however,
is not likely warranted.

Shared lockers or coat hooks probably pose even less risk as sources of
contamination. Any lice or nits that might detach in a swimming pool would likely
be removed by the pool filter or should otherwise perish before they have a
chance to contact a person. Closing a swimming pool because of lice is a
hysterical overreaction.

Should I use insecticides in the house to rid it of lice? Insecticidal treatments
targeted at lice within the school or home, in vehicles, or to carpets and furniture
are generally unwarranted, and unnecessarily expose occupants to insecticidal
residues.

Can anything be used to repel lice? The application of any substance to the hair
with an expectation of repelling lice is unwarranted and may neither be safe nor
effective. Head lice do not seem to be readily acquired naturally, and they may
pose less risk than any "repellent" product.

How can I have specimens evaluated? Health care professionals and others may
send us samples to confirm the identity of suspected lice and eggs. Patients are
encouraged to first approach their doctor or nurse for assistance and to discuss
treatment. Although we endeavor to reply to inquires, the volume of such
requests may limit our ability to answer all requests. Submitted samples are
considered for entomological identification, and are not considered as clinical
laboratory specimens.

Management Schemes We have created two flowcharts to assist the parent and
school administrator in managing head lice infestations.

These plans may be viewed at:
Scheme for managing presumed headlice infestations
Scheme for managing presumed headlice infestations in school
________________________________________
This document has been assembled to assist health workers and patients access
information relevant to the diagnosis and treatment of head louse infestations.
Brand names have not been mentioned, nor do we endorse any particular
commercial product. This web site is intended for informational purposes and is not
meant to substitute for the advice provided by a medical professional. Always
consult a physician if you have personal health concerns.

Costs associated with assembling this information and responding to inquiries are
borne by our general laboratory funds. Please feel free to contact us if you found
this information useful and are inclined to assist with support of our work. We
encourage inquiries regarding the support of further research.


    ________________________________________
This page is maintained by:
Richard J. Pollack, Ph.D. rpollack@hsph.harvard.edu
Anthony Kiszewski, D.Sc. akisz@hsph.harvard.edu
Andrew Spielman, Sc.D. (see feature in HSPH web digest)
Department of Immunology and Infectious Diseases (DIID)
Laboratory of Public Health Entomology
Harvard School of Public Health
665 Huntington Avenue
Boston, Massachusetts 02115-6021 USA
last updated: August 9, 2000
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Copyright, 2000, President and Fellows of Harvard College