The efficacy of oral azithromycin in clearing ocular chlamydia: Mathematical modeling from a community-randomized trachoma trial

Fengchen Liu, Travis C. Porco, Harran A. Mkocha, Beatriz Munoz, Kathryn J. Ray, Robin L. Bailey, Thomas M. Lietman, Sheila K West

Research output: Contribution to journalArticle

Abstract

Mass oral azithromycin distributions have dramatically reduced the prevalence of the ocular strains of chlamydia that cause trachoma. Assessing efficacy of the antibiotic in an individual is important in planning trachoma elimination. However, the efficacy is difficult to estimate, because post-treatment laboratory testing may be complicated by nonviable organisms or reinfection. Here, we monitored ocular chlamydial infection twice a year in pre-school children in 32 communities as part of a cluster-randomized clinical trial in Tanzania (prevalence in children was lowered from 22.0% to 4.7% after 3-year of annual treatment). We used a mathematical transmission model to estimate the prevalence of infection immediately after treatment, and found the effective field efficacy of antibiotic in an individual to be 67.6% (95% CI: 56.5-75.1%) in this setting. Sensitivity analyses suggested that these results were not dependent on specific assumptions about the duration of infection. We found no evidence of decreased efficacy during the course of the trial. We estimated an 89% chance of elimination after 10 years of annual treatment with 95% coverage.

Original languageEnglish (US)
Pages (from-to)10-17
Number of pages8
JournalEpidemics
Volume6
DOIs
Publication statusPublished - Mar 2014

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Keywords

  • Azithromycin
  • Elimination
  • Mathematical model
  • SAFE strategy
  • Trachoma

ASJC Scopus subject areas

  • Epidemiology
  • Infectious Diseases
  • Public Health, Environmental and Occupational Health
  • Microbiology
  • Parasitology
  • Virology
  • Medicine(all)

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