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Jennifer S. Lee, Sheila K. West, Harran Mkocha, Charlotte A. Gaydos, Thomas C. Quinn, Beatriz E. Munoz; The Effect of Multiple Rounds of Mass Drug Administration on the Association between Ocular Chlamydia trachomatis Infection and Active Trachoma. Invest. Ophthalmol. Vis. Sci. 2012;53(14):70.
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Annual mass drug administration (MDA) is recommended for trachoma control in communities with a baseline prevalence of follicular trachomatous inflammation (TF) of 10% or greater, with the aim of reducing TF prevalence to less than 5%. Monitoring the impact of antibiotic treatment, which targets the infectious bacterium Chlamydia trachomatis, relies on the assessment of TF, one of the clinical signs of active trachoma. The aim of this study was to examine the relationship between ocular C. trachomatis infection and active trachoma prior to and following multiple rounds of MDA.
Thirty-two communities with endemic trachoma in Kongwa District, Tanzania were selected for annual mass treatment. Presence of ocular C. trachomatis infection and active trachoma was assessed in 3,200 index children (100 children aged five years and younger from each community), who were sampled at random at six-month intervals. Chlamydial infection was detected using the AMPLICOR PCR assay and active trachoma was identified by clinical examination performed by standardized graders using the WHO simplified grading system. The correlation between chlamydial infection and active trachoma was evaluated prior to treatment at baseline, and 12 and 24 months after baseline.
At baseline, the overall prevalence of chlamydial infection and active trachoma was 22% and 32%, respectively, and the prevalence of chlamydial infection among children with clinical signs of active trachoma was 49%. After two rounds of treatment, the prevalence of chlamydial infection among children with clinical signs of active trachoma declined to 36%. The correlation between chlamydial infection and active trachoma decreased with each MDA; among children with clinical signs of active trachoma, the odds of being infected with C. trachomatis decreased by 27% (OR 0.73, 95% CI 0.60 to 0.89, p=0.0016) with each treatment round.
This study indicates that the correlation between ocular C. trachomatis infection and active trachoma decreases with each successive round of mass treatment, as the overall prevalence of chlamydial infection and active trachoma declines. This suggests that the use of clinical examination to monitor the impact of MDA may overestimate the level of residual chlamydial infection in a community that has undergone multiple rounds of antibiotic treatment.
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