Rapid assessment of trachoma prevalence--Singida, Tanzania. A study to compare assessment methods

This article presents a methodology for the rapid assessment of trachoma that was validated against a prevalence survey, undertaken simultaneously in the same 12 villages in central Tanzania. The rapid assessment protocol suggests examinations for active trachoma in 50 children ages 1-10 in at least 20 households chosen from the high-risk neighborhoods in each village. Women over the age of 15 in the same households were examined for trichiasis. In the rapid assessment, 244 households were visited, with 691 children and 470 women examined. In the prevalence survey, 377 households were visited, with 1855 children and 1310 women examined. Rankings of the villages using population prevalence of active disease and rapid assessment prevalence of active disease are highly correlated (Spearman correlation = 0.59, p < 0.05). In fact, the three villages with the highest prevalence in the population data were identified as the villages with the highest prevalence by the rapid assessment. Although rankings of the villages using population prevalence of trichiasis and rapid assessment prevalence of trichiasis are positively correlated, this correlation is not significantly different from zero, the village with the highest trichiasis prevalence according to the random sample being ranked as 8th by the rapid assessment. The cost of the rapid assessment was roughly one-third the cost of the prevalence survey. Thus, it appears that the rapid assessment method can quickly and inexpensively determine which villages have the greatest amount of active disease in children, and roughly estimate the burden of trichiasis in the community.