Patient Information: Sexually Transmitted Diseases (STDs)
Pediculosis (Crabs and Pubic Lice)
What is Pediculosis?
Pediculosis is an animal parasite which usually is found in the pubic hair of men and women. Also called crabs or pubic lice, it may also be found on the hair of the chest, underarm and face. Crabs do not live on scalp hair.
What are the Symptoms of Pediculosis?
The main symptom of pediculosis is itching. The itching is thought to be caused by an allergy to the bite of the louse. You may not always have itching. There may also be tiny dark brown spots on the skin or undergarments where they come in contact with the affected area.
How is Pediculosis Spread?
Crabs are most often spread during bodily contact with a person who has crabs. Occasionally, lice may be spread by towels, clothing, bed sheets or toilet seats. Adult lice can live up to ten days, while eggs (nits) live no longer than one month in clothing or bedding.
Prevention of Pediculosis.
If you suspect someone or something is infested with crabs, avoid contact. Use caution in sharing towels, clothing, bed sheets, sleeping bags, etc. Do not scratch the area because you may carry the lice to other parts of your body covered by hair.
How is Pediculosis Diagnosed?
Although they are small, adult lice can be seen by the naked eye. They attach to pubic hair, are gray-brown and move. The nits (eggs) attach to the base of pubic hair and are small, oval and gray. A magnifying glass may be used to see the nits or lice. Some may be removed with tweezers, placed on a glass slide and examined under the microscope in the doctor's office.
How is Pediculosis Treated?
You and your partner(s) should be treated at the same time. The treatment for crab lice is a shampoo or lotion (Kwell), available by prescription. There are effective over-the-counter treatments (RID) also available.
- Kwell shampoo should be applied to wet hair of all affected areas (except eyelashes and eyebrows), worked into a lather and left on for four minutes before rinsing. A second treatment is seldom needed; but , if necessary, treatment can be repeated in 24 hours. The shampoo should only be applied twice in one week.
- Kwell lotion is applied to the affected area, left on for 12 hours and treatment repeated one week later.
- RID is massaged into dry affected hairy areas, left on for 10 minutes and washed off.
After any of these treatments, remaining nits may be removed by a fine tooth comb. If the eyelashes or eyebrows are affected, it is usually necessary to have the lice removed by a clinician using another method.
Clothing and linen should be washed and dried in a hot dryer. This should be done at the same time as treating yourself. Clothing unable to be washed and dried should be hung in a closet for four weeks before use. Furniture, if infested, should also be left alone for four weeks.
When do I Return to the Clinic?
A follow-up visit is not needed, but if the problem persists or comes back you should return for further treatment.
Peer Review Status: Internally
Peer Review Date: 2004