Pubic lice (pediculosis pubis or crab lice) are very tiny insects that infest the pubic hair and survive by feeding on human blood. These parasites are most often spread by sexual contact; in a few cases, they may be picked up through contact with infested bedding or clothing. An estimated 3 million people with new cases of the infestation are treated each year in the United States.
Symptoms. The primary symptom of infestation is itching in the pubic area. Scratching may spread the lice to other parts of the body; thus, every effort should be made to avoid touching the infected area, although this may be difficult.
Diagnosis. Pubic lice are diagnosed easily because they are visible to the naked eye. They are pinhead size, oval in shape, and grayish, but appear reddish-brown when full of blood from their host. Nits, the tiny white eggs, also are visible and usually are observed clinging to the base of pubic hair.
Treatment. Lotions and shampoos that will kill pubic lice are available both over the counter and by prescription (see our "hair" section). Creams or lotions containing lindane, a powerful pesticide, are most frequently prescribed for the treatment of pubic lice. Pregnant women may be advised not to use this drug, and a physician's recommendations for use in infants and small children should be followed carefully. Itching may persist even after the lice have been eradicated. This is because the skin has been irritated and requires time to heal. A soothing lotion such as calamine may offer temporary relief.
Prevention. All persons with whom an infested individual has come into close contact, including family and close friends as well as sex partners, should be treated to ensure that the lice have been eliminated. In addition, all clothing and bedding should be dry-cleaned or washed in very hot water (125° F), dried at a high setting, and ironed to rid them of any lice. Pubic lice die within 24 hours of being separated from the body. Because the eggs may live up to six days, it is important to apply the treatment for the full time recommended.
Scabies is a skin infestation with a tiny mite, Sarcoptes scabiei. Scabies has become relatively common throughout the general population. It is highly contagious and is spread primarily through sexual contact, although it also is commonly transmitted by contact with skin, infested sheets, towels, or even furniture.
Symptoms. Scabies causes intense itching, which often becomes worse at night. Small red bumps or lines appear on the body at sites where the female scabies mite has burrowed into the skin to lay her eggs. The areas most commonly affected include the hands (especially between the fingers), wrists, elbows, lower abdomen, and genitals. The skin reaction may not develop until a month or more after infestation. During this time, a person may pass the disease unknowingly to a sex partner or to another person with whom he or she has close contact.
Diagnosis. Scabies may be confused with other skin irritations such as poison ivy or eczema. To make an accurate diagnosis, a doctor takes a scraping of the irritated area and examines it under a microscope, to reveal the presence of the mite.
Treatment. As with pubic lice, lindane is an effective treatment for scabies. Pregnant women should consult a doctor before using this product. Nonprescription remedies such as sulfur ointment also are available. Sulfur is fairly effective but may be objectionable because of its odor and messiness. Itching can persist even after the infestation has been eliminated because of lingering skin irritation. A hydrocortisone cream or ointment or a soothing lotion may provide relief from itching.
Prevention. Family members and sex partners of a person with scabies are advised to undergo treatment. Twenty-four hours after drug therapy, a person with scabies infestation is no longer contagious to others, even though the skin irritation may persist for some time. As with pubic lice, special care must be taken to rid clothing and bedding of any mites.
Prepared by (and copied with permission from): Office of Communications National Institute of Allergy and Infectious Diseases National Institutes of Health Bethesda, MD 20892
Public Health Service U.S. Department of Health and Human Services June 1998