Lice are small, wingless, blood-sucking insects which infest the head and bodies of humans. Human lice are spread from person-to-person mainly by close contact or by sharing personal belongings like hair combs, brushes, caps and other clothing.
There are three types of human lice that live on humans, the Head Louse, the Body Louse and the Pubic (Crab) Louse. Amongst them, only the body louse is known to transmit diseases.
The most commonly reported louse is the Head Louse. People of any age can get head lice, but young school age children are the most commonly infected. They are mostly spread by head-to-head contact. Head lice have three stages: the egg (nit), the nymph, and the adult.
Many schools and daycare centers have adopted the "no nit" policy recommended by the National Pediculosis Association and Santa Clara County Vector Control District. This policy means children cannot attend school if nits (eggs) are found in their hair. Head lice treatments do not remove nits from the head because the nits are glued to the base of hairs. A fine-toothed nit comb needs to be used to remove the nits. Removing all nits from the hair is the only way to prevent the spread of head lice.
For more information on three types of human lice, please select the following topics: