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Dianne E. Stare, Beatriz E. Munoz, Harran Mkocha, Charlotte Gaydos, Thomas Quinn, Sheila K. West; Clinical Signs of Trachoma as Indicators of Community Infection with C. Trachomatis. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1478.
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Trachoma is the leading infectious cause of blindness worldwide. The World Health Organization (WHO) recommendation for trachoma control calls for three years of mass treatment for districts with trachoma >10%. Post-treatment, the clinical signs of infection may persist despite a drop or even clearance of infection. Thus, mass treatment of communities may continue when not needed. Our study sought to evaluate if various combinations of the clinical signs of trachoma, using an expanded grading scheme, might predict the absence, or very low prevalence, of infection at the community level.
71 villages located in seven districts in Tanzania were surveyed. A random sample of households and of children ages five and under within households was identified. After guardian consent, children were evaluated for clinical signs of trachoma and a swab was taken for determination of C. trachomatis infection. A modified WHO grading scheme was used to accommodate milder and more severe disease signs. Proportions of children positive for infection were evaluated against all possible combinations of follicular trachoma (TF) and inflammatory trachoma (TI). The sensitivity and specificity of each combination was then compared against the community infection level.
7828 children were assessed for trachoma and infection. Mean community prevalence of infection was 5.4%; mean community prevalence of trachoma was 11.6% ranging from 0 to 38%. Children with severe TI, regardless of the presence of TF, had infection rates above 50%. While findings of severe TI, a combination of TF and TI (WHO criteria) or severe TF with any sign of inflammation were strongly associated with infection in children, the absence of these signs was not a specific indicator that the community had no or low infection rates.
In the setting of the 71 communities in Tanzania, the use of a set of expanded signs to determine infection status of a community was not specific. The development of a rapid, point-of-care test for Chlamydia remains the best option for surveillance to identify communities that might have MDA stopped.
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