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Sheila K West, Beatriz E Munoz, Jerusha Weaver, Zakayo Mrango, Laura Dize, Charlotte Gaydos, Thomas Quinn, Diana Martin, Andrea Zambrano; Once Trachoma is gone, what tools can we use for surveillance? . Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6204.
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Once trachoma rates at district level are <5% in children ages, 1-9 years, Country national trachoma control programs stop Mass Drug Administration and move to surveillance. However, it is unclear what tool or combination of tools, might be used for surveillance in these districts. Kilosa district in Tanzania stopped MDA four years ago and underwent a prevalence survey to investigate the relationship between the prevalence of trachoma, use of a test of infection with C. trachomatis, and an antibody test for prior exposure to trachoma to understand potential risk of re-emergence of disease.
Random selection of 30 hamlets, with probability proportional to size, was carried out from a complete list of rural hamlets. Within each hamlet, 50 children ages 1-9 years were randomly selected for survey. For each child the upper conjunctiva was graded for presence of follicular trachoma (TF), and a swab taken and processed for C. trachomatis using the Aptima Combo 2 Assay (Hologic/Genprobe, San Diego, CA). A dried blood spot was also taken and analyzed for antibodies to pgp3 and CT694 using the Luminex 100 platform.
The prevalence of trachoma in Kilosa was 0.4%, showing trachoma has essentially been eliminated in the district. The prevalence of infection was 1.1%, 50% in those few cases with TF. The profile of antibody responses showed that children ages 3 and under have the lowest prevalence of antibodies to pgp3. In the five communities where the prevalence in children ages 3 and under was >10%, two of the communities also had either trachoma or infection.<br />
In Kilosa district, trachoma has been eliminated. All tools-clinical assessment, test of infection, and test of antibody status -were concordant. The low prevalence of antibody to pgp3 in the youngest children provided further evidence of interruption of transmission in this district.
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