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Jennifer Lee, Beatriz Munoz, Harran Mkocha, Charlotte Gaydos, Sheila West; Decline of ocular Chlamydia trachomatis infection and follicular trachoma with annual rounds of mass treatment in mesoendemic communities in Tanzania. Invest. Ophthalmol. Vis. Sci. 2013;54(15):871.
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The World Health Organization (WHO) recommends mass drug administration (MDA) with azithromycin in communities with a baseline prevalence of follicular trachoma (TF) of 10% or higher, but there is little evidence speaking to the number of annual rounds of treatment required to sustainably reduce C. trachomatis infection and TF to levels at which MDA is no longer required. The aim of this study was to examine the prevalence of C. trachomatis infection and TF over time in a mesoendemic setting.
Forty-eight communities with mesoendemic trachoma in Kongwa District, Tanzania were selected for annual MDA and monitored over 24-48 months. Prior to each annual round of treatment, 100 children aged up to nine years from each community were randomly selected for examination. Presence of ocular C. trachomatis infection was detected using the Roche AMPLICOR PCR assay and active trachoma was identified by standardized field graders using the WHO simplified grading system. Treatment coverage in children was above 80% in all communities for every treatment round. Infection and disease prevalence was estimated over time using random effects models to account for clustering at the community level.
The median baseline prevalence of C. trachomatis infection in the 48 communities was 15.5% (IQR: 6.5-26.5%), with an average decline of 3.2% per year. The median baseline prevalence of TF was 20.0% (IQR: 13.0-36.5%), with an average decline of 5.4% per year. According to our models, it would require five rounds of MDA to reduce prevalence of infection to 0%, and four rounds of treatment to reduce prevalence of TF to 5%.
The study findings suggest that, in mesoendemic settings, four rounds of MDA may be required to reduce prevalence of TF to 5%, a level at which trachoma would no longer considered a public health threat.
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