Head lice (Pediculus capitis) infestation is very common, experienced by 6-12 million people around the world annually, most of them children aged 3-10 and their families. Females get head lice more often than males, and in the United States, African-Americans rarely get head lice. The reasons for these two facts are not known.
Lice is spread through direct contact with the body, clothing or other personal items of a person already carrying lice.
There are three forms of lice: the nit, the nymph and the adult: nits are the eggs of the louse, the nymph is an immature louse and the adult is a fully-grown louse. Full-grown lice are about the size of a sesame seed.
Head lice and body lice (Pediculus humanus) are similar in appearance, although the head louse is smaller. Pubic lice (Pthirus pubis), on the other hand, are quite distinctive. They have pincer-like claws, making them look like crabs (hence, the nickname for pubic lice: "crabs").
The most common symptom of lice infestation is itching. Excessive scratching of the infested areas can cause sores, which may become infected. In addition, body lice can be a vector for typhus, lapsing fever or trench fever.
Lice is usually treated with medicated shampoos or cream rinses. Nit combs can be used to remove nits from the hair. Lately resistance to the usually used commercial products is rising. A dire need for safe and effective alternatives is necessary.