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Health Encyclopedia - Diseases and Conditions

Head Lice

Definition of Head Lice
Description of Head Lice
Treatment of Head Lice
What Questions To Ask Your Doctor About Head Lice

Definition of Head Lice

Head lice are parasites (about the size of a small ant) that often develop in the hair of children and sometimes adults.

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Description of Head Lice

The head louse, Pediculus capitis humanus, is by no means a new nuisance. The insect has been an unwelcome companion to humans, probably from the beginning, as with its close relatives, the body louse and the pubic (or crab) louse. Head lice infestations seem to be on the rise in recent years - as almost any parent of an elementry-age child can tell you. A parent's first reaction to head lice is often revulsion, sometimes accompanied by a sense of shame, due to the misperception that head lice only live on "dirty" people. In truth, the only thing that the presence of head lice tells about children is that they've been around other kids with head lice.

Head lice get their nourishment by sucking small amounts of blood from humans. Their favorite feeding area is the scalp, behind the ears, and at the nape of the neck. Their feeding and sucking activity is responsible for the itching that is so frequently the first hint of infestation. If left untreated, a rash and infection can occur. In severe cases, the lymph glands in the neck may swell. Although usually confined to the head, head lice can sometimes set up shop in beards, eyebrows and rarely, eyelashes.

Though they don't fly, lice are quite adept at getting from head to head, especially when those heads are close together. Good hygiene is always an admirable goal, but a clean head of hair is no guarantee that they won't invade. Because children play so closely together and are often in large groups, lice have an easy time traveling from child to child. Cases of lice seem to increase in the winter, possibly because kids are inside and close together - sharing hats, combs, and consequently, "cooties," as kids sometimes call them.

Head lice can live up to two to three days apart from the body, and in closets where clothes hang close together, may hop from hat to scarf. They also may be lurking on the headrest of a school bus seat, just waiting to get aboard an attractive head. (The stitching of those upholstered headrests can hide the tiny gray-white lice eggs called nits.)

It is easier to spot the nits than the lice themselves, and because nits are dandruff-like in appearance, they are easier to see on brunettes than blondes. To distinguish them from dandruff or hair spray, pick up a strand of hair close to the scalp and pull your fingernail across the area where the whitish substance appears. Dandruff or hair spray will come off easily, but nits will stay firmly attached to the hair. If you look very closely, you may be able to see the bugs themselves on the back of the head and around the ears.

Once you have discovered head lice on one family member, all members of the family, as well as close friends, should be checked. Also, look for lice and nits in the fabric of stuffed toys, upholstered furniture and bedding.

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Treatment of Head Lice

For all types of pediculosis, lindane lotion (Kwell or Scabene) is used extensively. A thin layer is applied to the infested and adjacent hairy areas and then removed after two hours by thorough washing. Remaining nits may be removed with a fine-toothed comb or forceps.

Permethrin 1% cream rinse (Nix), is a topical pediculocide and ovicide for the treatment of head lice and eggs. It is applied to the scalp and hair and left on for 10 minutes before it is rinsed off with water. Synergized pyrethrins (A-200 Pyrinate, Pyrinyl and Rid) are over-the-counter products that are applied undiluted until the infested areas are entirely wet. After 10 minutes, the areas are washed thoroughly with warm water and soap, and then dried.

Nits may be treated as indicated above. For involvement of eyelashes, petrolatum is applied thickly, twice daily for eight days and the remaining nits are then plucked off. There is a controversy about whether or not lice and the acarus of scabies can develop resistance to lindane.

Malathion lotion 0.5% (Prioderm) compared with A-200 Pyrinate shampoo, R&C shampoo, Rid, Kwell shampoo (lindane) and A-200 Pyrinate liquid, is the only product for pediculosis capitis that shows excellent ovicidal (egg-killing) activity. Hatching of eggs following treatment with the other agents leads to recurrence of the infestation.

Nit-picking

While parents hate to be "nit-pickers," nit-picking is usually the worst problem associated with head lice. To get rid of all the nits after a de-lousing shampoo, a special fine-toothed metal nit comb is used to dislodge the eggs, or they are picked off with fingernails or tweezers - a tedious procedure.

Nit combs (fine-toothed metal combs, sometimes with tiny blades at the base) can cut the hairs to which a louse egg is attached and it can take hours per head, depending on the length of hair and the number of nits. Although effective for thick hair, nit combs are useless for the very fine hair of a young child. Each egg-bearing hair can be cut out with scissors. Fingernails can also be used for nit removal.

Some experts recommend soaking the hair in warm, diluted vinegar to make nit-picking easier, a strategy of unproven usefulness. A haircut may make nit removal less time-consuming, but it can stigmatize children.

Preventing Re-infestation

To prevent reinfestation, the following may be helpful:

Make sure all family members and friends of the infested person have been closely scrutinized for signs of lice. If any of them appear to have lice, make sure they are treated.
Wash all clothing and bed linens used by the infested members of your family in hot water and place in a hot dryer for at least 20 minutes. If this cannot be done, place the linens and clothing into an airtight bag for two weeks. Dry cleaning also kills lice and nits.
Vacuum backs of chairs, pillows in living and bedroom areas, mattresses, car seats, headrests and rugs that might be in contact with infested hair. Empty and discard the vacuum bag. There are some OTC sprays for disinfecting furniture and bedding which contain insecticides that are not suitable for humans or animals, so be very careful not to confuse them with the products for human use.
Disinfect combs, brushes, sports helmets and other objects that come in contact with the head by soaking in medicated shampoo or very hot soapy water.
Recheck all family members and friends seven to 14 days and 21 to 28 days after initial treatment to be sure lice have not reappeared. (Eggs that remain after treatment will hatch in seven to 14 days.)

Though discovering that your child has head lice is no picnic, neither is it a cause for panic or shame. The problem is shared by a good portion of the American school population and can be controlled through vigilance and appropriate treatment.

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