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When Can Antibiotic Treatments for Trachoma Be Discontinued? Graduating Communities in Three African Countries

Ray, KJ; Lietman, TM; Porco, TC; Keenan, JD; Bailey, RL; Solomon, AW; Burton, MJ; Harding-Esch, E; Holland, MJ; Mabey, D (2009) When Can Antibiotic Treatments for Trachoma Be Discontinued? Graduating Communities in Three African Countries. PLoS Neglected Tropical Diseases, 3 (6). e458. ISSN 1935-2735
SGUL Authors: Harding-Esch, Emma Michele

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Background Repeated mass azithromycin distributions are effective in controlling the ocular strains of chlamydia that cause trachoma. However, it is unclear when treatments can be discontinued. Investigators have proposed graduating communities when the prevalence of infection identified in children decreases below a threshold. While this can be tested empirically, results will not be available for years. Here we use a mathematical model to predict results with different graduation strategies in three African countries. Methods A stochastic model of trachoma transmission was constructed, using the parameters with the maximum likelihood of obtaining results observed from studies in Tanzania (with 16% infection in children pre-treatment), The Gambia (9%), and Ethiopia (64%). The expected prevalence of infection at 3 years was obtained, given different thresholds for graduation and varying the characteristics of the diagnostic test. Results The model projects that three annual treatments at 80% coverage would reduce the mean prevalence of infection to 0.03% in Tanzanian, 2.4% in Gambian, and 12.9% in the Ethiopian communities. If communities graduate when the prevalence of infection falls below 5%, then the mean prevalence at 3 years with the new strategy would be 0.3%, 3.9%, and 14.4%, respectively. Graduations reduced antibiotic usage by 63% in Tanzania, 56% in The Gambia, and 11% in Ethiopia. Conclusion Models suggest that graduating communities from a program when the infection is reduced to 5% is a reasonable strategy and could reduce the amount of antibiotic distributed in some areas by more than 2-fold.

Item Type: Article
Additional Information: © 2009 Ray et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Keywords: Tropical Medicine, 06 Biological Sciences, 11 Medical And Health Sciences
SGUL Research Institute / Research Centre: Academic Structure > Infection and Immunity Research Institute (INII)
Journal or Publication Title: PLoS Neglected Tropical Diseases
Editors: Ngondi, JM
ISSN: 1935-2735
16 June 2009Published
16 June 2009Published Online
15 May 2009Accepted
Publisher License: Creative Commons: Attribution 4.0
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