Trachoma and ocular Chlamydia trachomatis rates in children in trachoma-endemic communities enrolled for at least three years in the Tanzania National Trachoma Control Programme

Abstract

Trachoma, a blinding eye disease caused by repeated and prolonged infection with Chlamydia trachomatis, is a significant public health problem for sub-Saharan Africa. Tanzania has had a National Trachoma Task Force since 1999, working on trachoma control in endemic districts. The objective of this study was twofold: first, to determine the current status of infection and clinical trachoma in these districts in Tanzania, and second, to determine if a combination of clinical signs could be used as a surrogate for infection. We conducted a survey for trachoma and infection with C. trachomatis in 75 villages in eight districts of Kongwa, Kilosa, Mpwapwa, Bahi, Kondoa, Manyoni, Monduli and Iramba in Tanzania, which have previously been shown to be endemic. In each village, a random sample of households, and of children within households, was taken for examination. Trachoma was graded using the World Health Organization system, which we expanded, and a swab taken to determine presence of infection. The rates of trachoma ranged from 0% in Iramba District to 15.17% in Monduli District, with large variation in villages within districts. Infection rates were generally lower than trachoma rates, as expected, and most districts had villages with no infection. A combination of clinical signs of trachoma in children, when absent, showed very high specificity for identifying villages with no infection. We conclude that these signs might be useful for monitoring absence of infection in villages, and that districts with trachoma prevalence between 10% and 15% should have village level rapid surveys to avoid unnecessary mass treatment.