What are body lice?

Definition

Body lice (Pediculus humanus corporis) are tiny parasites, up to one-eighth inch in length, that feed on human blood. They live and lay eggs (nits) in clothing folds and seams, then move to the skin to feed. An infestation or large number of body lice on one person is known as pediculosis, which is more of an embarrassment than a serious disorder.

Once off their host, lice usually die within five to seven days at room temperature, although the lice have been known to live up to thirty days. Body lice are larger and less common than their relatives, the pin-sized head or pubic lice.

Causes

Body lice infestations most often occur in overcrowded areas with poor hygiene. The parasites spread by direct contact. Lice do not jump or fly. Instead, they readily move from infested to noninfested persons, clothing, and linens.

Risk Factors

Risk factors for acquiring body lice include direct contact with infected people, clothing, or linens; not bathing regularly; wearing infected clothing; and using infected linens. Other risk factors include sleeping on reused mattresses and linens and on communal beds. Infestations are common among transients and have been known to occur during natural disasters or war.

Symptoms

Body lice cause severe itching, especially at night, and red skin bumps. The lice most often accumulate under waist bands or in armpits. If present for any significant time, the infestation may cause skin sores around the waist and groin.

Long-term infestations can lead to a general tiredness and an increased chance
of other diseases, such as relapsing or trench fever and louse-borne epidemic typhus. Louse-borne typhus is caused by a bacteria (Rickettsia
prowazekii) that is found in louse droppings. Symptoms include a high
fever, body ache, chills, cough, and a severe headache.

Screening and Diagnosis

Diagnosis is readily made by observation of the skin and clothing. It is not
uncommon to self-diagnose a case of body lice. Adult body lice are light-colored
(whitish-grey) and have six legs. Persons with body lice may also have
head and pubic lice.

Treatment and Therapy

Treatment usually involves bathing and disposing of infected clothing and
linens (such as towels and sheets). The clothes and linens can also be washed in
very hot water (130° Fahrenheit) and machine dried on high heat for a minimum of
twenty minutes. If lice or skin irritation continue, a physician may advise an
over-the-counter (OTC) or prescription treatment. Calamine
lotion, OTC steroids, or antihistamines may reduce the
itching.

With careful treatment, regular bathing, and the use of clean clothing and linens (linens changed once or more per week), it is possible to completely eradicate all body lice.

Prevention and Outcomes

To prevent lice from spreading, it is important to maintain careful hygiene and
avoid contact with infected people, clothing, or linens. During a major lice
outbreak, an insecticide may be used to prevent the spread of typhus.

Bibliography

Ashford, R. W., and W. Crewe. The Parasites of “Homo sapiens”: An Annotated Checklist of the Protozoa, Helminths, and Arthropods for Which We Are Home. 2d ed. New York: Taylor & Francis, 2003.

Despommier, Dickson D., et al. Parasitic Diseases. 5th ed. New York: Apple Tree, 2006.

Diaz, J. H. “Lice (Pediculosis).” In Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John E. Bennett, and Raphael Dolin. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.

“Ectoparasites.” In Textbook of Family Medicine, edited by R. E. Rakel et al. 7th ed. Philadelphia: Saunders/Elsevier, 2007.