Head lice infestation (pediculosis), one of the most common contagious
childhood diseases is caused by barely visible insects found almost
exclusively on the human scalp. Contrary to popular belief, head
lice infestation has little to do with personal hygiene. In fact,
head lice are totally non-discriminating, and can infest people
of any lifestyle, age, race, or socio-economic status. Since lice
multiply and spread quickly from host to host.
What do head lice look like and how do they grow?
Head lice are grayish in colour, and are barely visible to the
naked eye. Identifying lice can be difficult as they move very
rapidly upon six legs. Lice require warmth and humidity to survive,
and so tend to be most concentrated around the back of the host's
head and behind the ears. A single female may lay up to 150 eggs,
or "nits", during her lifetime. Nits are silvery-white in colour,
oval in shape, and may look to the naked eye like tiny grains
of sand cemented to the hair shaft. Nits are smaller than adult
lice, but are generally easier to identify because they're more
numerous and don't move. Seven to nine days after being laid,
the nits hatch and give birth to young lice who then start their
own life cycle.
Common questions about lice transmission
Question: Is the presence of lice a sign of poor personal
hygiene? Answer: No, head lice seem to prefer a clean scalp; and
otherwise show no particular preference for a human host's sex,
race, age or socio-economic status.
Question: Are children only susceptible? Answer: No, lice show no preference for children over adults.
However, infestation is more common among children between 3 and
10 years because of their tendency to be in close contact with
others - especially at school, day cares, buses, camps and playgrounds.
Question: Does long hair encourage infestation? Answer: No, since head lice are only interested in the
immediate area of the scalp, cutting the hair will neither prevent
nor alleviate infestation.
Question: Can Lice be contracted from plants, animals and
pets? Answer: No, humans are the only hosts head lice survive
on. Head lice cannot live onanimals, pets or plants.
Question: Can lice jump or fly from one person to another? Answer: Head lice have no wings, they can only crawl -
so transmission comes only from direct contact with other infested
people or their belongings. Indirect transmission can occur through
sharing personal articles that come in contact with the scalp,
such as hats, scarves, hair accessories, headgear, headphones.
How is head lice infestation detected?
The main symptoms of head lice infestation are itching and irritation
of the scalp. Itching is usually persistent, and more intense
during the night. Head lice infestation can be diagnosed by confirming
the presence of living lice or viable nits on the head. They are
visible to the naked eye, or with the use of a magnifying glass.
Although nits are generally easier to detect than lice, they can
be confused with specks of dandruff, skin debris, or hair product
residue. This mistake can be avoided by testing the adhesiveness
of the specks to the hair shaft. Unlike other substances, nits
cannot be removed easily with fingernails or by washing the hair.
It's important to be aware that the mere presence of nits in the
hair does not necessarily indicate current head lice infestation.
What happens if lice are found on a child?
If living head lice or viable nits are found on a student, the
school authorities usually send the infested child home with a
letter to the child's parents, explaining what the problem is
and suggesting that the child see a pharmacist or physician for
treatment. Parents and children are usually assured that they
are not to blame for head lice infestation, that there's no need
for panic, anxiety or embarrassment, and that the problem can
be resolved quickly and effectively with the proper treatment
and precautionary measures.
If more than one student is found to have head pediculosis, a
sample of children from each grade should be examined by the nurse
in order to estimate the degree of the outbreak. If the infestation
becomes difficult to control, the nurse may need assistance from
the local public health department to fully evaluate and control
How are head lice infestations treated?
There are three important treatment components:
A variety of pediculicidal treatments are available in the
form of shampoos, creme rinses, and aerosols. Properly administered,
the application usually kills all lice, but some nits may
survive. Most pediculicidal treatments require a second application
after a given period of time, in order to wipe out any lice
which may have hatched from surviving nits. The specific treatment
should be discussed with the child's doctor, nurse or pharmacist.
For successful treatment, instructions for how to use the
product must be strictly adhered to. Misuse or repeated dosages
of pediculicides can render treatment ineffective, make the
problem worse, or even cause harm.
Use of a fine-toothed comb after pediculicidal treatment
The use of a special comb to remove nits and head lice after
application of a pediculicide is essential to successfully
completing treatment. Immediately after rinsing the pediculicide
from the hair, the fine-toothed comb should be used on a small
lock of hair at a time, combing towards the scalp and then
back, to remove all nits and lice. This operation should take
about two hours and requires a great deal of patience, but
must be done in order to avoid reinfestation.
Disinfection of items that may have been in contact with
Head lice can live for about 48 hours away from the host,
and nits can survive for up to two weeks. So another important
precaution for preventing reinfestation (or infestation of
other family members) involves the disinfection of personal
articles and other items that are likely to have come in contact
with the scalp. These may include hats, scarves, hair accessories,
towels, and bedding items. Clothing which may have come in
contact with the patient's hair should be washed in very hot
water and dried in the hottest cycle of the dryer for at least
20 minutes. The same should be done for towels and bedding
items. Brushes and combs can be disinfected by soaking in
hot water for 10 minutes. Items that cannot be washed should
be either dry-cleaned, ironed with a hot iron, or sealed in
a plastic bag for two weeks.
What about family and other close contacts?
In order to reduce chances of re-infestation and to control the
outbreak of head lice, it's important that anyone who's been in
close contact with the infested person - whether family members,
schoolmates or friends - be informed, examined, and if necessary,
treated. Any other infested individuals should be treated at the
The information provided in this site is
designed to be an educational aid only. It is not intended to
replace the advice and care of your child's physician, nor is
it intended to be used for medical diagnosis or treatment. If
you suspect that your child has a medical condition, always
consult a physician.