Importance of coverage and endemicity on the return of infectious trachoma after a single mass antibiotic distribution

Takele Lakew, Wondu Alemayehu, Muluken Melese, Elizabeth Yi, Jenafir I House, Kevin C Hong, Zhaoxia Zhou, Kathryn J Ray, Travis C Porco, Bruce D Gaynor, Thomas M Lietman, Jeremy D Keenan, Takele Lakew, Wondu Alemayehu, Muluken Melese, Elizabeth Yi, Jenafir I House, Kevin C Hong, Zhaoxia Zhou, Kathryn J Ray, Travis C Porco, Bruce D Gaynor, Thomas M Lietman, Jeremy D Keenan

Abstract

Background: As part of the SAFE strategy, mass antibiotic treatments are useful in controlling the ocular strains of chlamydia that cause trachoma. The World Health Organization recommends treating at least 80% of individuals per community. However, the role of antibiotic coverage for trachoma control has been poorly characterized.

Methodology/principal findings: In a collection of cluster-randomized clinical trials, mass oral azithromycin was administered to 40 villages in Ethiopia. The village prevalence of ocular chlamydia was determined before treatment, and at two and six months post-treatment. The mean prevalence of ocular chlamydia was 48.9% (95% CI 42.8 to 55.0%) before mass treatments, decreased to 5.4% (95% CI 3.9 to 7.0%) at two months after treatments (p<0.0001), and returned to 7.9% (95% CI 5.4 to 10.4%) by six months after treatment (p = 0.03). Antibiotic coverage ranged from 73.9% to 100%, with a mean of 90.6%. In multivariate regression models, chlamydial prevalence two months after treatment was associated with baseline infection (p<0.0001) and antibiotic coverage (p = 0.007). However, by six months after treatment, chlamydial prevalence was associated only with baseline infection (p<0.0001), but not coverage (p = 0.31).

Conclusions/significance: In post-hoc analyses of a large clinical trial, the amount of endemic chlamydial infection was a strong predictor of chlamydial infection after mass antibiotic treatments. Antibiotic coverage was an important short-term predictor of chlamydial infection, but no longer predicted infection by six months after mass antibiotic treatments. A wider range of antibiotic coverage than found in this study might allow an assessment of a more subtle association.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1. Kernel density estimate showing the…
Figure 1. Kernel density estimate showing the distribution of antibiotic coverage.
Antibiotic coverage data was available for 38 of 40 villages. The density plot was computed using the Epanechnikov kernel function, Sheather-Jones plug-in bandwidth estimate, and upper boundary correction using the renormalization method.
Figure 2. Predicted chlamydial infection after a…
Figure 2. Predicted chlamydial infection after a single mass azithromycin treatment, with varying levels of antibiotic coverage.
Post-treatment chlamydial prevalence in 1–5 year old children was calculated for a hypothetical community treated with a single mass azithromycin treatment, in which 48.9% of 1–5 year old children were infected at baseline. Antibiotic coverage was significantly associated with post-treatment infection at two months (2A; R2 = 0.53, p = 0.007), but not at six months (2B; R2 = 0.35, p = 0.31). The upper and lower curves are the boundaries of the 95% confidence interval for the predicted mean.

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Source: PubMed

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