RESUMO
Head lice infestation have become a great problem in school children, reaching epidemic proportions in some countries. An open study was conducted to determinate how widespread head lice infestation were among preschool and elementary school children in Bilbao (North of Spain). We studied 23,624 children from whole public school of the city, aged 3 years to 14 years. The results of head lice control were: total prevalence 9.39% (between 1.8% and 31.6%). We found more girls than boys become infested (1.7% 1.0). Higher infestation levels were found between third and fifth grades (9 years to 11 years). At the same time, whole social-economic levels (low, middle and upper) resulted infesting by head louse, so there is not immunity against this parasite, although higher infestations degrees were found in low levels. At last we realized that head louse infestation is usually a family condition, so that treatment should not be confined only to the school children, and it is necessary besides health-school, whole the social-help.
