Pubic lice and body lice

What are pubic lice and body lice?

Pubic lice are tiny insects about 1-2 mm long (smaller than the head of a match). Their medical name is Phthirus pubis and they are grey or brown in colour.

• "Crabs". Sometimes they are called crabs because their second and third pairs of legs have crab-like claws. These claws are used to hold on to hairs tightly. Lice are blood-sucking insects which survive by feeding on tiny amounts of your blood, which they obtain through your skin. Female lice lay eggs (also called nits) which are smaller than a pinhead. These eggs stick to the hairs in which the lice live. The eggs hatch into lice after 6-10 days. A female louse can lay up to 300 eggs in her lifetime of 1-3 months.

• Parts of the body affected. Pubic lice live in hairy areas of the body.

  • Pubic hair. Because they prefer thick coarse hair, pubic lice commonly affect the pubic hair. However, they may also affect body hair.

  • Around the back passage (anus).

  • Underarms, beard.

  • Chest.

  • Rarely, eyebrows and even eyelashes.

Note: pubic lice do not live in the hair on your head, as scalp hair tends to be softer and finer, and the lice can't hold on to these hairs. Head lice are a different type of louse (called Pediculus humanus capitis). Pubic lice only affect humans. They can't be caught from, or passed to, animals.

• Body lice are slightly longer than pubic lice (about 3-4 mm) but have a narrower body. Their medical name is Pediculus humanus. They are also known as clothing lice because the lice and their eggs can be found in the seams of clothing. Body lice can be found anywhere in the body but tend to avoid the scalp, except at the margins.

How do you get pubic lice?

• Sexual transmission. You need close body contact to pass pubic lice on to others. Usually pubic lice are caught by having sex with a person who already has a pubic louse infestation.

• Close non-sexual physical contact. It is possible to 'catch' pubic lice through close non-sexual physical contact with an affected person - such as kissing someone who has lice in their beard.

• Unlikely to catch from the non-direct contact. Pubic lice and their eggs attach very strongly to hair; they won't wash or brush off, nor do they fall off. They cannot survive for long without a human 'host' to feed from. This means that you are very unlikely to catch pubic lice from clothing, bed linen, shared towels or toilet seats.

How do you get body lice?

You can catch body lice by coming into close physical contact with someone who has lice. This need not be sexual contact. You can also catch it from lice-infested clothing, bedding or towels. Body lice are mainly seen in homeless people who are unable to wash frequently or change their clothes regularly.

Pubic lice symptoms

• Itching. The main symptom is generalised itching in the affected areas, usually in the pubic hair region. Itching may take between one and three weeks to begin after you become infected. Itching is usually worse at night, when the lice feed. It is due to a sensitivity to louse saliva.

• Red bumps. Itchy red 'bumps' on the skin, in the hair-covered areas, may appear.

• Blue spots. Faint blue spots may appear on the skin. This occurs where the lice have been feeding.

• Irritation. Skin irritation and scratching may cause redness or a rash in affected areas, or the skin may appear thickened.

• Eye inflammation. You may develop eye inflammation if your eyelashes are affected.

• Dark spots of underwear. You might notice really tiny dark brown specks in your underwear or your skin - this is lice poo (faeces).

• No symptoms. Some people have no symptoms but can still pass lice on to others without realising they are doing so.

Body lice symptoms

Some people do not get any symptoms but notice the lice or nits on their body or clothes. Itching at night is common and usually occurs on the trunk, the armpits or the groin. This happens because body lice usually live in clothing during the day, only moving on to the skin when feeding on the person's blood. As with pubic lice, there may be small red lumps and blue spots.

Pubic lice treatment

Pubic lice infestation is treated with insecticide specially formulated to be used on the human body. It kills the pubic lice. The whole body should be treated, twice - seven days apart. You should avoid getting insecticides in the eyes.

The two commonly used insecticides to treat pubic lice are malathion lotion and permethrin 5% cream. Water-based (aqueous) products are preferred over alcohol-based treatments (which may cause even more skin irritation). They are easy to put on and normally work well if used properly. The following is a general guide, giving tips for success:

Malathion is suitable for all people. Permethrin is NOT usually used if you are under 18.

• Application. You should put the lotion or cream on all your body, including the scalp. This is because the lice can spread and affect many parts of your body and sometimes even the scalp. You should pay particular attention to hairy parts of your body, especially to pubic hair, hair around your back passage (anus), beards, moustaches and eyebrows. Note: this advice is based on national guidelines and may be different to what is said on the insecticide packet. The packet may say only put on from the neck down - but experts recommend that the whole body be treated (taking care to avoid getting the insecticide in the eyes).

• Dosage. An average adult needs about 100 ml of lotion or 20-30 g of cream to cover the whole body.

• Dry skin. Put lotion or cream on cool, dry skin. If you have a hot bath or shower, wait until the skin cools down and is fully dry before putting on.

• Leave on time. You should leave the lotion or cream on for the full recommended time and then wash it off. Malathion and permethrin should both be left on for 12 hours (overnight) and then washed off.

• Reapplication. If you wash any part of your body during the treatment period, you should put the lotion or cream on the washed areas again.

• Don't shave. You do not need to shave the affected areas. The lotion or cream will clear the lice.

• Washing. Some people advise washing bed linen, towels and clothes (particularly underwear) which have been used since a week before symptoms started. There is no good evidence that this is necessary but some people prefer to do it.

• Eyelashes treatment. If your eyelashes are affected, ask a doctor for advice on how to treat these areas. Simple eye ointment or Lacri-Lube® ointment is greasy, like Vaseline®, and often put on the eyelashes with cotton buds to suffocate the lice. Permethrin lotion at a lower strength (1%) may be appropriate for the eyelids if you are over 18 and not pregnant or breastfeeding. You should keep your eyelids closed while putting it on and wash it off after 10 minutes.

• If you're pregnant. Tell your doctor or pharmacist if you are pregnant or breast-feeding, as some treatments may not be suitable.

• Repeat the same treatment after seven days. Although lice are usually killed by one application, not all eggs may be. The second application makes sure that any lice that hatch from eggs that survived the first application will be killed before they are old enough to lay further eggs. Note: this advice is based on national guidelines and may be different to what is said on the insecticide packet. The packet may say that one application is sufficient - but experts recommend two applications, seven days apart.

Body lice treatment

Because body lice mainly live in clothing and bedding, putting treatment onto the skin is less important. The main treatment is directed at destroying the nits and lice in clothing and bedding. This can be achieved by laundering in hot water (at least 55°C), ironing with a hot iron, drying in a hot dryer or dry cleaning. If there are lots of lice present you may need to use an insecticide on the body.

Clothing and bedding are sometimes treated with insecticide if there is an outbreak in a community.

Do family and friends need treatment?

Pubic lice treatment for friends and family

Recent close contacts and sexual partners within the previous three months should be examined for lice and treated if infected. Remember, you can have pubic lice without symptoms.

Body lice treatment for friends and family

People in contact with the body, clothing or bedding of a person with body lice should be examined for lice themselves. Their clothing and bedding should also be treated and they may need to step up their hygiene routine.

Some other points about pubic lice

• Itching often takes a few days to settle after successful treatment.

• Consult a doctor if symptoms persist after the second application of lotion or cream. This is because pubic lice sometimes become resistant to one type of insecticide and a different insecticide may be needed.

• Avoid close body contact with others until you finish the second treatment application.

• If you got pubic lice from a sexual contact then you should be tested for other STIs. Your doctor may do this or refer you to a genitourinary medicine (GUM) clinic.