Lice are adapted to their host and they need permanently the high temperatures and humidity produced by the human skin as well as a permanent source of blood. Therefore, lice, which do not have any possibility to jump or fly and can’t survive more than 24 hrs outside the human body, leave the infested individual only to arrive to another person. Normally head lice infest a new host only by close contact between individuals, making social contacts among children and parent/child interactions the more likely routes of infestation than shared combs, brushes, towels, clothing, beds or closets. Head to head contact is by far the most common mode of lice transmission. The number of children per family, sharing of beds, social contacts, and socio-economic status were all reported as significant risk factors in head louse infestation (8).
In Israel, 10-15% of all children 4-13-years old are actively infested with head lice at any given moment. Additional 15-20% of the children have nits (dead eggs or empty eggs shells) on their hair, showing that they were infested during the last 8 months, treated successfully and now louse free, but show signs of previous infestations. Though children in this age group are the most infested group of the population it was shown that 59.2% of mothers become infested with lice during their adulthood. Mothers of 3 or more children were more often infested than those with 1-2 children. Mothers who reported professional contact with children other than theirs (kindergarten staff, teachers) were significantly more often infested with lice that those who did not report such contact. The fact that mothers are in closer physical contact with their children, wear longer hair, are those, who in most cases examine and treat their children for head lice, and are more represented in professional groups such as kindergarteners and primary school teachers, make them more prone for lice infestation (8, 9).
Several epidemiological studies conducted in the country showed that girls are 2-10 times more infested with lice than boys, which could be explained by the wearing of longer hair, which makes transmission of lice much easier that the usually shorter hair of boys (8, 10).
Though there are some indications showing that given children in the family are more prone for infestation with lice than their siblings, this could not be confirmed in epidemiological studies. The age and gender of the child are the more important factors which apparently influencing the infestation (9).