Body lice
Body lice (Pediculus humanus corporis) are small parasites, measuring up to one-eighth of an inch, that feed on human blood. They typically inhabit the folds and seams of clothing, laying eggs (nits) nearby, and move to the skin to feed. Infestations, known as pediculosis, can lead to severe itching and skin irritation, particularly in areas such as the waist and armpits. While body lice are more common in overcrowded and unsanitary conditions, they do not jump or fly, spreading instead through direct contact with infested individuals or their belongings.
Risk factors for body lice infestations include lack of personal hygiene, wearing infested clothing, and using shared linens or mattresses. Treatment generally involves thorough bathing and washing contaminated clothing or linens in hot water. Over-the-counter remedies may be used to alleviate itching. Preventive measures focus on maintaining good hygiene practices and avoiding contact with infested items; during outbreaks, insecticides may be employed to control the spread of lice and associated diseases, such as louse-borne epidemic typhus. With proper care and hygiene, body lice can be effectively eradicated.
Body lice
- ANATOMY OR SYSTEM AFFECTED: Blood, skin
- ALSO KNOWN AS: Pediculosis, Pediculus humanus corporis
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 via 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 waistbands 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 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-gray) 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. In advanced cases, body lice infestations can be controlled with chemical insecticides.
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
"About Body Lice." Centers for Disease Control, 24 June 2024, www.cdc.gov/lice/about/body-lice.html. Accessed 3 Feb. 2025.
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.