Head lice are not found on floors in primary school classrooms

The control of head lice is frequently based on perceptions rather than evidence, as illustrated by the belief that vacuuming carpets is an essential component of treating head lice, and the less common practice of application of insecticides to floors as an adjunct to head lice treatment.

To 1) evaluate the importance of floors as a source of infection for head lice in primary schools to provide evidence on which to base decisions about the need to treat floors; 2) determine the prevalence of active pediculosis and average intensity of infection in primary school children in Townsville, north Queensland.

In Townsville, north Queensland, we examined preschool and primary classroom floors for lice by using a filter on a vacuum cleaner when the children were absent from the rooms. Active pediculosis was treated, head lice were collected and counted.

Of the 2,230 children examined from 118 classrooms, 466 had head lice, a prevalence of 20.9%. A total of 14,033 lice were collected from these children to give an average intensity of infection of 30.1 (95% CI 21.9-38.3) lice per infected child and 129.9 (95% CI 90.7-169.2) lice per infected class. Of the 118 classrooms, 108 (91.5%) had at least one child with active pediculosis. No lice were recovered from the classroom floors.

Classroom floors are not a risk in the transmission of head lice and no special anti-louse measures are required.