Prevalence of Trachoma in Schoolchildren in Brazil

Trachoma was hyperendemic in Brazil until the 20th century. The prevalence has declined sharply in the past decades. The aim of this study was to estimate trachoma prevalence in schoolchildren in Brazilian municipalities with a Human Development Index (HDI) below the national mean.

A cluster random sampling survey on trachoma prevalence was carried out. Brazilian municipalities with HDI below the national mean, within each of the 27 states, were stratified into three strata according to population size. In each stratum, schools were systematically selected to comprise a sample of 2400 schoolchildren, totaling 7200 per state. In each selected school, children enrolled from 1st to 4th grade were examined for trachoma. The simplified trachoma grading system was used. At a meeting held in each school, the study was explained to parents, and verbal consent sought.

A total of 185,862 children were enrolled in the selected schools. Of these, 171,973 (92.5%) participated in the study. The overall prevalence of trachomatous inflammation - follicular was 5.0% (95% confidence interval 4.7-5.3%), varying from 1.5% to 9.0% among the states. Prevalence was significantly associated with the sampling stratum (being higher in small municipalities), the zone in which the school was located (higher in rural schools), and with age (higher among younger children).

Trachoma is still a public health problem in Brazil, although at a low level of endemicity. As the country advances towards the elimination of blinding trachoma, this survey provides a baseline for evaluation of ongoing and future elimination interventions.