It's back to school time again, which means children will re-unite with old friends and make new ones. But summer vacation stories might not be the only thing kids share when they go back to school, they could also share summer head lice.
The U.S. Center for Disease Control says that in the United States, infestation with
head lice is most common among pre-schoolchildren attending child care,
elementary schoolchildren, and the household members of infested
children.
Although reliable data on how many people in the United States
get head lice each year are not available, the CDC estimates 6 million to 12
million infestations occur each year in the United States among
children 3 to 11 years of age.
Head lice move by crawling; they cannot hop or fly. Head lice are
spread by direct contact with the hair of an infested person. Anyone who
comes in head-to-head contact with someone who already has head lice is
at greatest risk. Spread by contact with clothing (such as hats,
scarves, coats) or other personal items (such as combs, brushes, or
towels) used by an infested person is uncommon. Personal hygiene or
cleanliness in the home or school has nothing to do with getting head
lice.
Here are some head lice facts from the CDC:
What do head lice look like?
Head lice have three forms: the egg (also called a nit), the nymph, and the adult.
Actual size of the three lice forms compared to a penny. (CDC Photo)
Illustration of egg on a hair shaft. (CDC Photo)
Egg/Nit: Nits are lice eggs laid by the adult female
head louse at the base of the hair shaft nearest the scalp. Nits are
firmly attached to the hair shaft and are oval-shaped and very small
(about the size of a knot in thread) and hard to see. Nits often appear
yellow or white although live nits sometimes appear to be the same color
as the hair of the infested person. Nits are often confused with
dandruff, scabs, or hair spray droplets. Head lice nits usually take
about 8-9 days to hatch. Eggs that are likely to hatch are usually
located no more than ¼ inch from the base of the hair shaft. Nits
located further than ¼ inch from the base of hair shaft may very well be
already hatched, non-viable nits, or empty nits or casings. This is
difficult to distinguish with the naked eye.
Nymph form. (CDC Photo)
Nymph: A nymph is an immature louse that hatches
from the nit. A nymph looks like an adult head louse, but is smaller. To
live, a nymph must feed on blood. Nymphs mature into adults about 9-12
days after hatching from the nit.
Adult louse. (CDC Photo)
Adult: The fully grown and developed adult louse is
about the size of a sesame seed, has six legs, and is tan to
grayish-white in color. Adult head lice may look darker in persons with
dark hair than in persons with light hair. To survive, adult head lice
must feed on blood. An adult head louse can live about 30 days on a
person's head but will die within one or two days if it falls off a
person. Adult female head lice are usually larger than males and can lay
about six eggs each day.
Adult louse claws. (CDC Photo)
Where are head lice most commonly found?
Head lice and head lice nits are found almost exclusively on the
scalp, particularly around and behind the ears and near the neckline at
the back of the head. Head lice or head lice nits sometimes are found
on the eyelashes or eyebrows but this is uncommon. Head lice hold
tightly to hair with hook-like claws at the end of each of their six
legs. Head lice nits are cemented firmly to the hair shaft and can be
difficult to remove even after the nymphs hatch and empty casings
remain.
What are the signs and symptoms of head lice infestation?
- Tickling feeling of something moving in the hair.
- Itching, caused by an allergic reaction to the bites of the head louse.
- Irritability and difficulty sleeping; head lice are most active in the dark.
- Sores on the head caused by scratching. These sores can sometimes become infected with bacteria found on the person's skin.
How did my child get head lice?
Head-to-head contact with an already infested person is the most
common way to get head lice. Head-to-head contact is common during play
at school, at home, and elsewhere (sports activities, playground,
slumber parties, camp).
Although uncommon, head lice can be spread by
sharing clothing or belongings. This happens when lice crawl, or nits
attached to shed hair hatch, and get on the shared clothing or
belongings. Examples include:
- sharing clothing (hats, scarves, coats, sports uniforms) or articles (hair ribbons, barrettes, combs, brushes, towels, stuffed animals) recently worn or used by an infested person;
- or lying on a bed, couch, pillow, or carpet that has recently been in contact with an infested person.
Dogs, cats, and other pets do not play a role in the spread of head lice.
How is head lice infestation diagnosed?
The diagnosis of a head lice infestation is best made by finding a
live nymph or adult louse on the scalp or hair of a person. Because
nymphs and adult lice are very small, move quickly, and avoid light,
they can be difficult to find. Use of a magnifying lens and a
fine-toothed comb may be helpful to find live lice. If crawling lice are
not seen, finding nits firmly attached within a ¼ inch of base of the
hair shafts strongly suggests, but does not confirm, that a person is
infested and should be treated. Nits that are attached more than ¼ inch
from the base of the hair shaft are almost always dead or already
hatched. Nits are often confused with other things found in the hair
such as dandruff, hair spray droplets, and dirt particles. If no live
nymphs or adult lice are seen, and the only nits found are more than
¼-inch from the scalp, the infestation is probably old and no longer
active and does not need to be treated.
If you are not sure if a person has head lice, the diagnosis should
be made by their health care provider, local health department, or other
person trained to identify live head lice.
Is infestation with head lice reportable to health departments?
Most health departments do not require reporting of head lice
infestation. However, it may be beneficial for the sake of others to
share information with school nurses, parents of classmates, and
others about contact with head lice.
Do head lice spread disease?
Head lice should not be considered as a medical or public health
hazard. Head lice are not known to spread disease. Head lice can be an
annoyance because their presence may cause itching and loss of sleep.
Sometimes the itching can lead to excessive scratching that can
sometimes increase the chance of a secondary skin infection.
Can head lice be spread by sharing sports helmets or headphones?
Head lice are spread most commonly by direct contact with the hair of
an infested person. Spread by contact with inanimate objects and
personal belongings may occur but is very uncommon. Head lice feet are
specially adapted for holding onto human hair. Head lice would have
difficulty attaching firmly to smooth or slippery surfaces like
plastic, metal, polished synthetic leathers, and other similar
materials.
Can wigs or hair pieces spread lice?
Head lice and their eggs (nits) soon perish if separated from their
human host. Adult head lice can live only a day or so off the human
head without blood for feeding. Nymphs (young head lice) can live only
for several hours without feeding on a human. Nits (head lice eggs)
generally die within a week away from their human host and cannot
hatch at a temperature lower than that close to the human scalp. For
these reasons, the risk of transmission of head lice from a wig or
other hairpiece is extremely small, particularly if the wig or hairpiece
has not been worn within the preceding 48 hours by someone who is
actively infested with live head lice.
Can swimming spread lice?
Data show that head lice can survive under water for several hours
but are unlikely to be spread by the water in a swimming pool. Head lice
have been seen to hold tightly to human hair and not let go when
submerged under water. Chlorine levels found in pool water do not kill
head lice.
Head lice may be spread by sharing towels or other items that have
been in contact with an infested person's hair, although such spread
is uncommon. Children should be taught not to share towels, hair
brushes, and similar items either at poolside or in the changing room.
Swimming or washing the hair within 1-2 days after treatment with
some head lice medicines might make some treatments less effective. Seek
the advice of your health care provider or health department if you
have questions.
Source: CDC
Images and Photo Credit: CDC
