Fast Five Quiz: Hygiene-Related Diseases

Richard H. Sinert, DO


May 04, 2021

Lice infestation remains a major problem throughout the world, making the diagnosis and treatment of lice infestation a common task in general medical practice. All socioeconomic groups can be affected.

Adults infested with Pthirus pubis are usually sexually active and have groin and body hair involvement. Involvement with pruritus of the groin, axillae, eyelashes, or eyebrows can help differentiate P pubis infestation from head or body louse infestation. Parents of children infested with P pubis on the eyelids and/or eyebrows should be questioned about also being infested because the parents are usually the source of infestation.

Unlike the head louse and the pubic louse, the body louse does not live on the human body. Pediculus humanus capitis prefers cooler temperatures; it lives in clothing, crawling onto the human body only to feed, predominantly at night. Females lay 10-15 eggs per day on the fibers of clothing, mainly close to the seams. Adult body lice can live up to 30 days but die within 1-2 days when away from the host and without blood meals. Patients infested with Pediculus humanus corporis experience nocturnal pruritus, particularly in the axillary, truncal, and groin regions, when the lice move from the clothing to the body to feed.

Physical examination findings in body louse infestation include multiple lesions from bites. Uninfected bites present as erythematous papules, 2-4 mm in diameter, with an erythematous base. Bites may be located anywhere on the body but tend to be concentrated in the axillae, groin, and trunk (ie, areas most often covered by clothing). Thus, the face, feet, and arms are not commonly affected. Body lice tend to avoid the scalp, except at the margins.

Use of a pediculicide is usually unnecessary with P humanus corporis infestation because the lice live on the clothing. Treatment of clothing and bed linens includes laundering in hot water, ironing with a hot iron, or drying in a hot dryer. Dry cleaning is also effective for killing lice and their nits on clothing. Education about hygiene and accessibility to laundering facilities are important in preventing the spread of body lice and reinfestation.

Read more clinical information about lice.


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