This disorder is most commonly seen in school-aged children or in children attending day-care centers. However, any age group can be affected. It is very uncommon in African Americans. The louse is passed from person to person via close contact. The organism may live away from a host on furniture, clothing, linens, hats, or hairbrushes for several weeks, and thus may be passed to another who comes in contact with these articles.
PATHOPHYSIOLOGY Head lice feed off human blood and therefore remain close to the scalp. When the louse lays its eggs, the ova, or nits, are cemented to the hair shaft. The ova hatch within 7 days. The ova encasement remains attached to the hair shaft and grows out with the hair. By the time the nits are a distance of 1 cm or more away from scalp, they have probably hatched.
CLINICAL FEATURES The patient usually experiences pruritus. This itching may be mild or quite intense. The occiput and posterior neck are common sites of pruritus, and excoriations on the neck may be noted.
DIAGNOSIS The diagnosis is made on clinical inspection of the scalp for lice and nits ( Fig 220.127.116.11.). Unlike flakes of scale, which can easily be moved up and down the hair shaft, nits are firmly attached to the shaft. If the diagnosis is in question, suspected organisms or ova can be viewed underneath a microscope.
TREATMENT Two important aspects of treatment should be addressed: treating the current infection and preventing reinfestation. Several agents may be used to treat the infestation. Permethrin 1% (Nix) rinse should be used as first-line therapy. Unlike lindane and pyrethrins, permethrin is ovacidal as well as pediculicidal. After shampooing, the treatment should be applied to the scalp for 10 min. For cosmetic reasons, nits can be removed by rinsing the hair in a 50% vinegar solution and then combing the hair with a fine-toothed comb.
To prevent reinfestation, all close contacts should be examined and affected individuals treated, including family members, classmates at school or day care, roommates, or health care workers in an institutional setting. Schools and day-care centers should be notified so that appropriate measures can be undertaken to evaluate other individuals.
Clothing, hats, and bed linens should be washed with hot water and dried in a dryer on high heat for 20 to 30 min. Carpets and sofas should be thoroughly vacuumed. Hairbrushes should be washed in hot water with the pediculicide product.
Patients should be reexamined in 7 to 10 days.
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