Body lice

Body lice (Pediculus humanus corporis) are small blood-sucking insects that live on the body of infested humans and in their clothing or bedding, particularly the seams. Body lice can spread from person to person and are normally associated with crowded and unhygienic living conditions, particularly in conditions of social upheaval such as natural disasters or wartime.

In overcrowded, unhygienic conditions where there is no opportunity to wash and launder clothing on a regular basis body lice can be responsible for the spread of epidemic infections such as epidemic typhus.

In Australia, body lice are not responsible for the spread of any infectious disease-causing organisms, and are uncommon. However, scratching the itch caused by louse saliva can cause secondary bacterial infection of the skin.
Body lice are different to head lice (that infest the scalp) or pubic lice (that infest the pubic hair).

What are body lice?

Body lice are flat wingless insects with six legs, each ending in a claw. They are greyish or brown in colour and range in size from 2mm to 5mm. Body louse eggs (nits) are small, white and oval-shaped.

Lice lay their eggs in the seams of any clothing worn next to the skin, such as underwear. A gluey secretion anchors each egg to clothing fibres, or sometimes to body hairs.

The eggs take five to 14 days to hatch, depending on the availability of the host’s body heat. If the infested item of clothing is removed at night and the eggs are deprived of continuous warmth, it will take longer for the eggs to hatch.

Seven days after hatching the egg matures into an adult louse. The female body louse lives for around four weeks and lays approximately eight eggs per day. Without a constant source of blood a louse will die within two to five days.

Mature lice survive by feeding on human blood and live exclusively inside clothing. Their strong grasping claws allow them to move through clothing and against the skin.

Body lice feed often and at any time of day or night and typically choose a site where the skin is soft, creased and close to clothing such as the armpit or waistline. The insect bites into the skin and sucks blood. Its grey body takes on a darkened colour as blood is ingested.

Symptoms and signs of body lice

The characteristics of a body louse bite include:•A tiny red dot initially appears.

• The red dot rises into a small cyst-like lump or papule.
• The area becomes inflamed.
• The bite causes irritation and severe itching.
• Secondary infection can result from continuous scratching.

Body lice are visible to the naked eye and occasionally a body louse can be seen crawling or feeding on the skin. Crawling lice can sometimes be seen in the seams of clothing or bedding.

Transmission of body lice

Body lice can be transmitted in clothing or bedding as well as by close physical contact. Direct contact with an affected person or their personal belongings can spread the lice from person to person. For example, homeless people or people in areas of natural disaster are prone to body lice infestations – their clothes are not washed often and people may come into contact with each other when seeking warmth at night. In close quarters, some of the body lice from one person can crawl across to the next person.

Treatment and control of body lice

To treat body lice:

• increase personal hygiene – bathe or shower regularly (at least weekly)
• change and launder clothes, especially underwear, regularly (at least weekly), or throw away affected clothing
• wash clothing and bedding recently used by an infested person in hot water (greater than 70ºC). Tumble dry on hot, or iron clothes, with all seams turned outwards
• if items cannot be washed or dry cleaned, seal them in a white plastic bag for a month, or iron them, paying special attention to seams
• thoroughly vacuum mattresses, paying attention to seams and creases, and under buttons
• if prescribed, use an appropriate insecticide treatment (available from pharmacies)
• use medication to reduce itching and control secondary infection, if necessary.

To prevent body lice infestation, avoid close contact with infested persons, their clothing and bedding.

To avoid bringing body lice into your home, check the seams of any second-hand clothing or bedding for the presence of body lice.

Where to get help

•Your doctor