Parasitic skin infections
Infestation with the head louse Pediculosis capitis.
Occurs mainly in school children.
F > M (due to longer hair).
Pediculosis capitis or head louse is a grey-white insect that grasps on to hair and sucks blood. Eggs laid by the female are closely adherent to hair. Insects are spread by contact but as insects can survive for hours away from the host, transfer on clothing, shared combs, towels and beds may occur.
Infestations are often asymptomatic although allergy may result in itching and lymphadenopathy. The head louse is difficult to find but eggs (nits) may be seen along the hair shaft. A fine-toothed nit comb is often used to detect lice and nits.
Topical shampoo containing insecticides such as malathion and permethrin may be used, although there is some evidence of increasing resistance. Treatment should be repeated after 7 days. Mechanical removal of lice nit combs from wet hair is an alternative strategy. Household members should be examined and treated if infested.