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J. B. Biebesheimer, T. Lakew, W. Alemayehu, J. House, K. C. Hong, V. Cevallos, Z. Zhou, B. D. Gaynor, J. P. Whitcher, T. M. Lietman; Long Term Follow-Up of Trachoma in Endemic Communities Treated With Six Biannual Mass Azithromycin Distributions. Invest. Ophthalmol. Vis. Sci. 2007;48(13):351.
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Trachoma is one of the leading causes of preventable blindness in the world. Mass azithromycin distribution is recommended by the World Health Organization to control infectious trachoma in endemic regions. Theoretically, repeated treatment at six-month intervals may lead to local elimination of trachoma in hyper-endemic areas. However, this has yet to be tested empirically. Here we survey all 1-5 year old children in two villages, treated at six-month intervals, who have completed 42 months of follow-up.
As part of a group-randomized clinical trial, all members of 16 villages in the Gurage zone of Ethiopia were offered either annual or biannual mass distribution of azithromycin for the treatment of ocular chlamydia infections. Children aged 1-5 years were assessed at six-month intervals for the prevalence of active clinical trachoma and for PCR-proven chlamydia infection. Based on high prevalence of trachoma at baseline, and length of available follow-up (42 months), two villages which received six biannual treatments were selected for further investigation. Each child in these villages was evaluated for clinically active trachoma (by World Health Organization criteria), and for chlamydial infection with PCR (Roche Amplicor).
The two villages contained 371 and 397 people. The average treatment coverage in the two villages was 89% and 93% of the entire population, including adults. Pre-treatment PCR prevalence of infection in children was 48% in each village. The final study treatment was delivered at 30 months. At 42 months, 12 months after the last treatment, there were zero PCR-positive samples among 81 and 96 children ages 1-5 in the two villages (representing 100% of children in this age group in each village). Pre-treatment clinical activity by the WHO criteria was 78% and 83% in each village. At 42 months, clinical activity was reduced to 17% and 24%, respectively.
Repeated biannual mass distribution of azithromycin can locally eliminate ocular chlamydial infection from pre-school age children in even the most severely affected communities. PCR prevalence of infection in children can be maintained at or near zero with biannual treatment. This benefit persists at least 12 months after treatment is stopped. Clinically active trachoma can be dramatically reduced, but lags behind PCR-detected infection.
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