Lice may cause such diseases as typhus or relapsing fever. Often, there are no symptoms, although in severe cases there is itching of the scalp, which can cause secondary infection through scratching the infected area. Crusting and oozing then occur, similar to that of impetigo. Head lice are most common among schoolchildren because of the frequency with which they put their heads together during work projects and games. If one child is infected, then all the other children are likely to be infected.
Treatment involves careful washing of the hair with a medicated shampoo.
After washing, the hair should be meticulously combed using a fine-toothed comb to remove any nits, and then inspected. A second combing may be necessary. The procedure should be repeated a week later and, on each occasion, the shampoo should be left to dry on the hair before it is washed off the next morning. There is intense itching in the pubic area and possible secondary infection in scratch marks. In severe infestations, the hair in the armpits, eyebrows, and eyelashes may also be involved.