Three kinds of lice affect humans; infestation with lice is known as
pediculosis. The louse
itself is a small
wingless flattened insect.
Pediculosis capitis, head louse infestation, affects the scalp,
although sometimes it involves the eyebrows, eyelashes, and beard; it is particularly
common in children. The lice feed on blood from the scalp, having
infested it by direct
contact with hair and with items such as combs, towels, and headgear. The bites cause severe
persistent itching and the
lesions may become infected. The glands of the neck may sometimes enlarge.
Adult lice may be noticed around the back of the head and behind the ears. The small ovoid eggs, or nits, are easier to detect, being firmly
attached to hair shafts.
These hatch in three to fourteen days unless
removed with a nit comb. In addition to combing, the scalp should be treated with benzyl
benzoate or gamma benzene
hexachloride (GBH). Members of the same household also
should be examined for infestation.
Pediculosis corporis, body louse infestation, occurs when lice inhabit the
seams of clothing worn next to the skin and feed on the skin. Under good hygienic
conditions it is uncommon. The bites of the lice appear as small red marks, and itching may lead to severe
scratch marks with secondary
bacterial infection. Lesions are
especially common on the shoulders, buttocks, and abdomen. Both the parasites and nits show up readily in clothing.
Laundering and hot ironing of
seams will kill the lice. The skin should be rubbed with GBH.
Lotions may soothe inflammation. Nits remain viable in
clothing for as long as one month, hatching when they are reexposed to body heat. Dissemination of lice occurs through
contact with infected persons, clothing, or bedding.
Pediculosis pubis is crab
louse infestation of the area of the genitals and anus and sometimes
other hair regions. Infestation may be venereal or
acquired from clothing, bedclothes or toilet seats. Severe irritation, with scratch marks, occurs. Application of benzyl
benzoate or GBH is an effective treatment. Prolonged use of such chemicals
should be avoided, however.
Lice are known to transmits typhus fever,
relapsing fever, and trench fever, but these infections are rare.