Thirty-two communities with endemic
trachoma in Kongwa District, Tanzania, were offered annual MDA as part of a district-wide
trachoma control program. Presence of ocular C. trachomatis
infection and TF were assessed in 3,200 randomly sampled children aged five years and younger, who were examined prior to each MDA.
Infection was detected using the Amplicor CT/NG assay and TF was identified by clinical examination using the World Health Organization (WHO) simplified grading system. The association between chlamydial
infection and TF in children was evaluated at baseline prior to any treatment, and 12 months after each of three annual rounds of mass treatment. Factors associated with
infection were examined using generalized estimating equation models. At baseline, the overall prevalence of chlamydial
infection and TF was 22% and 31%, respectively. Among children with clinical signs of TF, the proportion of those with
infection was 49% prior to treatment and declined to 30% after three MDAs. The odds of
infection positivity among children with clinical signs of TF decreased by 26% (OR 0.74, 95% CI 0.65 to 0.84, pā=ā<0.01) with each MDA, after adjusting for age. For children aged under one year, who did not receive treatment, the relationship was unchanged.
CONCLUSIONS/SIGNIFICANCE: The association between ocular C. trachomatis
infection and TF weakened in children with each MDA, as both
infection and clinical disease prevalence declined. However, there was still a significant proportion of TF cases with
infection after three rounds of MDA. New strategies are needed to assess this residual
infection for optimal treatment distribution.