A Longitudinal Analysis of Chlamydial Infection and Trachomatous Inflammation Following Mass Azithromycin Distribution

ABSTRACTBackground: Mass azithromycin distributions are effective for clearing ocular strains of Chlamydia trachomatis, yet infection frequently returns in areas with hyperendemic trachoma. A better understanding of the factors associated with chlamydial reinfection could be helpful to plan trachoma elimination strategies.Methods: This was a prospective cohort study conducted in a trachoma-hyperendemic region of Ethiopia in 2003. As part of a larger cluster-randomized trial, 21 villages were treated with a single mass azithromycin distribution and all children 5 years and younger were monitored for ocular chlamydia and clinically active trachoma at baseline and at 2 and 6 months following the treatment.Results: In 20 villages with available data, azithromycin treatment coverage was 88.7% (95% confidence interval [CI] 85.7–91.8%). In total, 1005 children tested negative for ocular chlamydia at the 2-month visit, of whom 41 became infected by 6 months (1.0 incident chlamydia infections per 100 person-months...