Lice
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published 20/11/2007
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SummaryLice are small wingless insects that are ectoparasites of mammals. They are mostly host specific, and two species are human parasites: Pthirus pubis (pubic louse) and Pediculus humanus, with two varieties, P. h. capitis (head louse) and P. h. corporis (body louse). They are obligatory parasites, subsisting on blood from the host, and have mouthparts modified for piercing and sucking. The mouthparts are drawn into the head of the louse when not in use.
The adult head louse is about 2 to 4 mm long with an elongated body that is flattened dorsoventrally. The head is only slightly narrower than the thorax. The three pairs of legs are about equal in length and possess delicate hooks at the distal extremities. The entire life is spent on the host's body. The eggs (nits) are deposited on hair shafts, generally one nit to a shaft. The nits hatch in about 1 week, and the freshly hatched larvae, which must feed within 24 hours of hatching or die, mature in about 15 to 16 days. The adult female lives for approximately 1 month and may deposit more than 100 eggs during her reproductive life. Body lice are slightly larger than head lice but are similar in appearance with a similar life cycle, although the nits are deposited on fibers of clothing. Head lice and body lice interbreed.
The adult head louse is about 2 to 4 mm long with an elongated body that is flattened dorsoventrally. The head is only slightly narrower than the thorax. The three pairs of legs are about equal in length and possess delicate hooks at the distal extremities. The entire life is spent on the host's body. The eggs (nits) are deposited on hair shafts, generally one nit to a shaft. The nits hatch in about 1 week, and the freshly hatched larvae, which must feed within 24 hours of hatching or die, mature in about 15 to 16 days. The adult female lives for approximately 1 month and may deposit more than 100 eggs during her reproductive life. Body lice are slightly larger than head lice but are similar in appearance with a similar life cycle, although the nits are deposited on fibers of clothing. Head lice and body lice interbreed.
Table of Contents
- The adult head louse is about 2 to 4 mm long with an elongated body that is flattened dorsoventrally
- Lice are found wherever people are found. Able to exist only briefly away from the human body, lice are spread by close personal contact and by sharing of clothing and bedding.
- The head louse localizes on the scalp and rarely on other hairy areas of the body.
- The body louse lives chiefly in the seams of clothing and is rarely seen on the skin.
- Treatment of all types of lice strives to eradicate lice and nits and prevent reinfestation.
- Body lice may be treated with the same medications, but parasites and nits are not generally found on the skin.
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