The head louse (Pediculus humanus var. capitis)
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Pediculosis

Pediculosis is an infestation of lice -- which are parasitic insects -- on the bodies of humans. The condition is more commonly known as head lice, body lice or pubic lice. more...

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Head lice (Pediculus capitis) infestation is most frequent on children aged 3-10 and their families. Females get head lice more often than males, and in the United States, African-Americans have head lice less often. The reasons for these two facts are not known.

Head lice are spread through direct head-to-head contact with an infested person. Body lice are spread through direct contact with the body, clothing or other personal items of a person already carrying lice. Pubic lice are most often spread by intimate contact with an infested person. Head lice occur on the head hair, body lice on the clothing, and pubic lice mainly on the hair near the groin. Human lice do not occur on pets or other animals. Lice do not have wings and cannot jump.

From each egg or "nit" may hatch one nymph that will grow and develop to the adult louse. Full-grown lice are about the size of a sesame seed. Lice feed on blood once or more often each day by piercing the skin with their tiny needle-like mouthparts. Lice cannot burrow into the skin.

Head lice and body lice (Pediculus humanus) are similar in appearance, although the head louse is often smaller. Pubic lice (Pthirus pubis), on the other hand, are quite distinctive. They have shorter bodies and pincer-like claws, making them look like crabs (hence, the nickname for pubic lice: "crabs").

The most common symptom of lice infestation is itching. Excessive scratching of the infested areas can cause sores, which may become infected. In addition, body lice can be a vector for louse-borne typhus, louse-borne relapsing fever or trench fever.

Lice on the hair and body are usually treated with medicated shampoos or cream rinses. Nit combs can be used to remove lice and nits from the hair. Laundering clothes using high heat can eliminate body lice. Efforts to treat should focus on the hair or body (or clothes), and not on the home environment.

Some lice have become resistant to certain (but not all) insecticides used in commercially available anti-louse products. A physician or pharmacist can prescribe or suggest treatments. Because empty eggs of head lice may remain glued on the hair long after the lice have been eliminated, treatment should be considered only when live (crawling) lice are discovered. Children with nits should not be sent home from school.

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A louse in the house
From Better Homes & Gardens, 9/1/04 by Debra Gordon

The phone rings. It's the school nurse. "Come get your child," she says. "He has lice." Before you rush out to pick him up, know this: Just about everything you've ever been told about head lice is wrong. For starters, your child shouldn't have to leave school. In 2002 the American Academy of Pediatrics stated specifically that there is no medical reason to make kids miss classes because of lice. In fact, all it does is make your child an easy target. "Other kids make fun of them and it's just terrible as far as a child's self-esteem goes," says Dr. Barbara L. Frankowski, a Vermont pediatrician who served on the committee that drafted the lice guidelines.

Head lice don't carry disease and they are not a sign of a dirty home or a dirty child. You don't get lice by sharing hairbrushes or hats. It's a bit of a mystery how lice get spread from person to person, but the most likely transmission route seems to be direct head-to-head contact.

Another myth: You need to wash stuffed animals, clothes, blankets, sheets, and vacuum everything in sight. Not true. Lice die quickly when off a human head--usually within 24 hours. If your child has an infestation, the only thing you need to treat is the lice itself.

Unfortunately, that has become more difficult these days because improper use of over-the-counter lice treatments containing the pesticides permethrin or pyrethrin has led to a growing number of resistant lice. Too few parents follow the directions to the letter, says Richard J. Pollack, Ph.D., of the Department of Immunology and Infectious Diseases at Harvard School of Public Health in Boston. For instance, the shampoos, such as Nix, have to be applied to dry hair, but many parents use it on wet hair. Make sure you follow the instructions explicitly.

If over-the-counter products don't work after two tries, ask your doctor for prescription lice killers. Two are available, the first being lindane. It's gotten a bad reputation in the popular press, says Pollack, and has even been banned in California. "But it's been grossly misused," he says. The drug is supposed to be applied for four minutes, then promptly washed out. But many parents put it on for far longer periods, causing skin reactions.

The other chemical, malathion, calls for a single 10-hour application, which should kill all the lice and their eggs, he says. It should only be used on kids 6 and older. And keep your kids away from open flames or cigarettes; malathion is dissolved in alcohol and extremely flammable.

Of course, you could also do what people have done throughout the centuries--shave your kid's head. Without hair to cling to, head lice will fall off and die. Some boys won't mind this option at all.

COPYRIGHT 2004 Meredith Corporation

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