(head louse) affects the scalp in children or adults, particularly in females. The adult lays its eggs on the scalp hair and the resulting ‘nit’ grows out with the hair. Secondary infection owing to scratching is common in severe infestations, causing enlarged lymph glands in the posterior neck. The lice and nits can be killed by applications of MALATHION 0.5 per cent lotion or PERMETHRIN 1 per cent lotion. After the hair is washed, application of a conditioner allows nits to be removed with a fine nit comb.

(crab louse) is broader and shorter than the head louse and less mobile. Usually transmitted sexually, it is found in the pubic area but may infect eyelashes and other body hair. It is easily seen, as are the large nits attached to the public hair: permethrin and malathion lotions are effective.

(body louse) differs from the head and crab louse in that it lives in clothing and only goes on to the body to feed. Infestation is found in vagabonds, armies in the field, or prisoners in conditions where even minimal hygiene is impossible. The lice are found in the seams of clothing together with multiple eggs. Typically signs of scratching and pigmentation are seen on the back of the infested person. Replacement of clothing or autoclaving or hot ironing of the clothes is curative.