Dermatology Associates of the Bay Area


Pediculosis (body lice)

Body lice are parasitic insects that live on the body and in the clothing or bedding of infested humans. Body lice infestations can spread rapidly under crowded conditions where hygiene is poor and there is frequent contact among people.

In the United States, body lice infestations tend to be found among transient populations who do not to have access to changes of clean clothes or bath. Infestation is unlikely to persist on anyone who bathes regularly and who regularly has access to freshly laundered clothing and bedding.

Where are body lice found?

Body lice are found on the body and on clothing or bedding used by infested people; lice lay eggs in the seams of clothing or on bedding. Occasionally eggs are attached to body hair.

Lice found on the hair and head are head lice, not body lice.

Can body lice transmit disease?

Yes. Epidemics of typhus, trench fever, and louse-borne relapsing fever have been caused by body lice. Though typhus is no longer widespread, epidemics still occur during times of war, civil unrest, natural disasters, in refugee camps, and in prisons where people live crowded together in unsanitary conditions. Typhus still exists in places where climate, chronic poverty, and social customs prevent regular changes and laundering of clothing.

What are the signs and symptoms of body lice?

Itching and rash are common; both are your body's allergic reaction to the lice bite. Long-term body lice infestations may lead to thickening and discoloration of the skin, particularly around the waist, groin, and upper thighs. Scratching may cause sores on the body. These sores can sometimes become infected with bacteria or fungi.

How are body lice spread?

Body lice are through direct contact (touching) with a person who has body lice, or indirectly through shared clothing, beds, linens, or towels.

What do body lice look like?

There are three forms of body lice: the egg (sometimes called a nit), the nymph, and the adult.

  • Nit: Nits are lice eggs. They are generally easy to see in the seams of clothing, particularly around the waistline and under armpits. They are about the size of a poppyseed. Nits occasionally may also be attached to body hair. They are oval and usually yellow to white. Body lice nits may take 1-2 weeks to hatch.
  • Nymph: The egg hatches into a baby louse called a nymph. It looks like an adult body louse, but is smaller. Nymphs mature into adults about 9-12 days after hatching. To live, the nymph must feed on blood.
  • Adult: The adult body louse is about the size of a sesame seed, has 6 legs, and is tan to greyish-white. Females lay eggs. To live, adult lice need to feed on blood. If the louse falls off of a person, it dies within about 5-7 days at room temperature.

How are body lice infestations diagnosed?

Body lice infestations are diagnosed by looking closely in the seams of clothing and on the body for eggs and for crawling lice. If you are unsure about infestation, diagnosis should be made by a health care provider if you are unsure about infestation.

How are body lice treated?

To treat infestations of body lice, the infested person should shower, change into clean clothes, and launder all infested clothing, bed linens, and towels. When laundering items, use the hot cycle (130°F) of the washing machine. Set the dryer to the hot cycle to dry items.

A 1% permethrin lotion or a pyrethrin lice-killing shampoo may be applied to the entire body of a person with extensive body hair. These lice-killing substances called pediculicides (pronounced peh-DICK-you-luh-side). may be applied to hairy regions, such as legs and armpits, of people with localized body hair.

Reference: Centers for Disease Control and Prevention