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Focus on body and pubic lice.

STOWE, VT. -- Location, location, location. Where lice live on the body and how they got there are important considerations for optimal diagnosis and therapy, according to Dirk M. Elston, M.D.

Although much attention is given to the identification and treatment of head lice, body lice and pubic lice are unique entities with specific treatment requirements. Dr. Elston said at a dermatology conference sponsored by the University of Vermont.

Similar in appearance to head lice, body lice (Pediculus humanus corporis) live in clothes rather than head hair. When they are not feeding, they hide in the seams of clothing and possibly the folds of bedding. Scratch marks, hives, and small raised red bumps on the shoulders, torso, or buttocks can be signs of body lice infestation.

Unlike head lice, body lice can be vectors for blood-borne diseases such as typhus and trench fever. In the United States, body louse infestation mainly affects homeless populations. Worldwide, infestations are common during times of war, in impoverished areas, and as a consequence of natural disasters that lead to living in crowded unsanitary conditions where clothing is not changed or laundered, said Dr. Elston of Geisinger Medical Center, Danville, Pa.

The treatment of body lice focuses on the infested clothing. Removing the clothing, laundering it in hot water, drying it on high heat, and pressing it with a hot iron are generally effective, but these tactics are often not feasible in the areas in which they are most needed, Dr. Elston said. In some settings, treating clothing with DDT, permethrin, or fumigants is useful.

Single-dose oral ivermectin has shown promise as an agent for mass treatment in the case of a widespread outbreak. Body lice may also respond to oral or topically applied pediculicides, although none of these agents are labeled or marketed for treatment of body lice in the United States.

Pubic lice (Phthirus pubis) are distinct in appearance from head and body lice; they have short, crablike bodies. Although they are most frequently found in the pubic region of the infested person, where they can cause intense itching and redness, they may also be found in other areas, such as in facial hair or eyelashes. In fact, Dr. Elston said, "eyelash nits are usually a manifestation of pubic louse infestation, not head louse infestation. I am amazed at how often it is misdiagnosed. When you see eyelash nits, you should be looking south, not north," he stressed.

Pubic lice infestation occurs mainly through sexual contact, and, as such, may be associated with other sexually transmitted diseases. Pubic lice may also be acquired by sharing a bed with an infested person. Children with pubic lice "have usually been infected [through] contact with an infested adult," the manner of which should be investigated, Dr. Elston said.

Particular care should be taken when pubic lice infestation is diagnosed as part of a rape investigation. "There is enough blood in a single louse to identify a rapist's DNA by [polymerase chain reaction]," he said. As such, mechanical removal of as many lice as possible may be important for evidentiary purposes.

Because the pubic louse egg is totally encased by a proteinaceous sheath, except for the operculum through which it feeds, it is more resistant to topical therapies than is the head louse. "The [egg] is relatively impermeable, so the best way to get to it is through the [host's] blood," Dr. Elston said. Thus, oral sulfa drugs as well as ivermectin have been successful.

BY DIANA MAHONEY

New England Bureau
COPYRIGHT 2005 International Medical News Group
No portion of this article can be reproduced without the express written permission from the copyright holder.
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Title Annotation:Infectious Diseases
Author:Mahoney, Diana
Publication:Internal Medicine News
Geographic Code:1USA
Date:Mar 15, 2005
Words:584
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