There are two kinds of lice: chewing lice, which feed on the skin and debris, and sucking lice, which feed on the blood.
Only sucking lice live on humans. Types include head lice, pubic lice, and body lice.
In this article, learn to identify lice by their appearance and where on the body they feed. We also describe the difference between lice bites and bed bug bites.
Identification
Head lice
Head lice bites
Pubic lice
Pubic lice bites
Body lice
Bed bug
Bed bug bites
Head lice
Head lice are small, gray insects about 2–3 millimeters (mm) in length. They live on the scalp, where they feed on human blood and lay eggs at the base of hair shafts.
The eggs of head lice are commonly known as nits, and they are tiny and translucent. The empty eggshells are white, and they can remain stuck to the hair for up to 6 months. A person is most likely to find them at the nape of the neck and behind the ears.
Head lice:
- do not transmit diseases, though their bites can occasionally expose the host to secondary infections
- lay around six eggs a day
- are transmitted through head-to-head contact and shared objects, including brushes, headwear, towels, and pillows
Treatment
People can use the following methods to treat head lice:
Medication
People can kill head lice using chemicals called pediculicides. Pediculicides are the active ingredients in over-the-counter (OTC) and prescription shampoos and lotions.
Some common pediculicides include:
- Permethrin or any of a group of organic compounds called pyrethrins: These work by attacking the nervous system of the lice. They are available without a prescription and are considered the first-line treatment against head lice. In recent years, however, some lice have developed a resistance to these treatments.
- Spinosad: This is a natural insecticide found in bacteria. It is the active ingredient in the prescription lotion Natroba, which is suitable for children aged 4 years and older.
- Ivermectin: This is available as a topical prescription medication under the brand name Sklice.
Unlike most pediculicides, which tend to kill only live insects, ivermectin can also kill newly hatched nits.
A 2012 study tested the effects of a lotion containing 0.5% ivermectin on louse eggs. The authors concluded that a single application was highly effective, even without combing for nits.
Combing
Because some shampoos and lotions may not kill nits, a person should use a nit comb after treatment. Combing helps remove louse eggs.
Even in combination, these methods are unlikely to eradicate all the eggs on the first try.
A person should repeat the chemical treatment and combing after 7–9 days, depending on the type of medication. This is to ensure that any newly hatched lice are killed.
Body lice are between 2.3–3.6 mm in length and tan or gray. They live in bedding and clothing and crawl onto the skin several times a day to feed.
They tend to bite areas of the body where the seams of clothing come into contact with the skin. These include the neck, shoulders, armpits, waist, and groin.
People with body lice may experience itching and rashes if they have allergic reactions to the bites.
Some thickening or darkening of the skin may also occur after prolonged periods of infestation.
Body lice:
- are most often spread through close contact with infected individuals
- are more common in areas with overcrowding and poor hygiene
- can carry bacterial diseases, including typhus, relapsing fever, and trench fever, though these conditions are rare, except in areas of extreme poverty
Treatment
People can use the following methods to treat body lice:
Housekeeping
Wash towels, bedding, and clothing in hot, soapy water and dry them in a machine using a high heat setting.
It is also best to spray furniture with a product that kills lice to eliminate eggs embedded in fabric fibers and seams.
Pediculicides
Treatment with pediculicides may also be necessary if body lice persist, despite improvements in housekeeping and personal hygiene.
Prevention
Practicing good housekeeping and personal hygiene is usually sufficient to prevent a body lice infestation.
Is it bed bugs?
When a person finds bites on their body, they may be unsure whether they have body lice or bed bugs. Bed bugs are not lice, but they also feed on human blood.
While body lice exist almost exclusively in areas with overcrowding and unsanitary conditions, bed bugs rarely indicate a lack of cleanliness or personal hygiene.
Bed bugs tend to enter the home on luggage, through shared bedding, or on used furniture.
At around 1–7 mm, bed bugs are larger than lice, and a bed bug infestation can create an almond-like smell. A person may also see discarded exoskeletons in bedding.
While body lice tend to bite during the day, bed bugs bite at night, when the host is lying in the infected area.
Due to their preference for dark places, they are difficult to spot without a flashlight.
Bed bug bites often appear as a line or group of three or more marks. These tend only to cause irritation in people with an allergic reaction to the bugs’ saliva.
Treatment
People can use the following methods to treat bed bugs:
Housekeeping
It is essential to wash infected bedding, linen, and clothing on a hot wash and dry cycle. Brush the mattress seams with a stiff brush to remove bed bugs and their eggs before vacuuming.
Special mattress covers are available, and these can prevent the bugs from entering or escaping. People should also vacuum and declutter the area around the bed.
Outlook
Body lice can carry diseases, but other types of lice usually cause no lasting harm. Accurate identification is essential for establishing the most appropriate treatment.
If a person is unsure of the cause of bites, they should speak to a doctor for a diagnosis.
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