Three kinds of lice affect humans; infestation with lice is known as pediculosis
. The louse itself
is a small wingless
, 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.
, 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.
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.