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Lice (Pediculosis)

Lice (pediculosis) is an infestation of the body with one of three species—head, body, or pubic lice, usually related to their location. Pubic lice, or crabs, are the most common type found on young adults. Head lice outbreaks are common among school children. Body lice are more commonly found in environments with crowded conditions, poor hygiene, or infrequent changes of clothing.

Since lice are parasites, they cannot live more than 48 hours without a host. Adult females lay tiny white oval-shaped eggs (nits) along a human hair shaft. In 6 to 10 days the nits hatch and after 10 more days the new lice are mature enough to lay eggs and continue the life cycle.

Symptoms

Head lice have elongated bodies and three pairs of legs, all about the same length. The nits can most easily be found in the scalp, above and behind the ears, and at the nape of the neck. In general, the only symptom associated with head lice is itching.

Pubic lice look like miniature crabs. They may be gray, tan, or reddish brown and are about the size of the head of a pin. They infest the hair in the genital region, but may also migrate to the thighs or abdomen, if hair is present. The lice and their nits are occasionally transferred by one’s fingertips to the armpits, beard, eyelashes, or eyebrows. The appearance of tiny red bite marks or flecks of dried blood may lead to the discovery of lice. Some people experience intense itching as a result of lice infestation. In others, the only symptom is the discovery of a louse or nit on the body.

Transmission

Lice may be transferred from one person to another by direct personal contact or by using the personal items of the affected person such as combs, hats, and bedding. Transmission can only occur if the lice remain alive or the nits are not destroyed.

Lice are discriminating. Human lice do not infest other animals, nor do animal lice infest humans.

Treatment

Treating lice involves application of medicated shampoo to all affected areas, which kills adult lice and nits. Read and follow the product directions carefully.

Nonprescription medications:

  • Nix (permethrin 1%), the preferred treatment
  • A-200 (piperonyl butoxide and pyrethrin shampoo)
  • RID (piperonyl butoxide and pyrethrins topical)
  • Ovide (0.5% malathion)

Prescription medications:

Occasionally prescription medication is necessary to treat head and pubic lice. If prescribed, follow the directions carefully.

General treatment measures:

  • All medication must remain in contact with the hair for a minimum specified time, usually ten minutes. Do not rinse it off before the specified amount of time has passed.
  • If nits are difficult to remove, a rinse consisting of two ounces of vinegar in two cups of water may be used a day after treatment to loosen nits.
  • Treatment may be repeated after seven days to ensure eradication of unhatched nits.
  • Reinfestation from personal items used during the active infestation is possible. All clothing, bedding, towels, etc., used within two days prior to treatment must be washed in hot, soapy water or dry-cleaned. Nonwashable items may be dry-cleaned or sealed in plastic bags for two weeks to allow time for all nits and lice to die.
  • After treatment, check hair every two to three days with a nit comb to remove nits and lice. Continue to check for two to three weeks until certain that all nits and lice are gone.
  • For a pubic lice infestation, avoid intimate contact with any sexual partner(s) until all have been treated.