We performed baseline examinations on 584 children aged 0–9 years. The mean prevalence of DNA evidence of ocular chlamydia was 41.9% (95% confidence interval [CI], 31.5–52.2; ). Antibiotic coverage in the 3 annual mass azithromycin distributions averaged 80.9% (±13.3%), 92.1% (±5.0%), and 87.3% (±11.8%) at the first, second, and third treatments, respectively.
Prevalence of Clinically Active Trachoma and Ocular Chlamydial Infection Before Mass Treatments (Month 0), and 1 Year After 3 Annual Mass Azithromycin Treatments (Month 36)
Follow-up monitoring was performed on 583 children from 370 households at month 36 (1 year after the last azithromycin distribution; ). In total, 25 children from 20 households and 7 communities had DNA evidence of ocular chlamydia (mean prevalence, 4.2% [95% CI, .3%–8.0%]; P = .002 compared to baseline), and 41 children from 35 households and 8 communities had RNA evidence (mean prevalence, 6.9% [95% CI, .4%–13.3%]). For both tests, the distribution of infection was highly skewed, with 80% of infected children living in just 3 of the 12 communities. Although the DNA- and RNA-based tests were closely correlated (Spearman ρ = 0.95, P < .001), the ocular chlamydia prevalence estimate was higher for the RNA-based test compared to the DNA-based test (P = .02). The correlation between the community prevalence of ocular chlamydia and the prevalence of clinically active trachoma (TF and/or TI) was similar when using the RNA-based test (ρ = 0.62, P = .03) or the DNA-based test (ρ = 0.64, P = .02). All swabs that were positive for DNA were also positive for RNA. No negative control swabs collected at month 36 tested positive for chlamydial DNA (n = 60) or RNA (n = 59).
We found evidence for clustering of chlamydial RNA within communities (ICC = 0.35 [95% CI, .06–.64]; likelihood ratio test P < .001) and within households of the same community (ICC = 0.78 [.55–1.00]; P = .001); we observed similar results for chlamydial DNA (ICC = 0.38 [.01–.48]; P < .0001 and ICC = 0.99 [.97–1.00]; P < .001, respectively). Clinically active trachoma was also found to cluster within both communities (ICC = 0.06 [95% CI, .01–.12]; likelihood ratio test P < .001) and households (ICC = 0.23 [95% CI, .04–0.42]; P = .03). We found no association between the detection of chlamydial RNA and sex (P = .35) or age (P = .88), nor between chlamydial DNA and sex (P = .15) or age (P = .21). In contrast, children with clinically active trachoma were more likely to be male (odds ratio [OR], 1.56 [95% CI, 1.05–2.31]) and <5 years of age (OR, 2.82 [95% CI, 1.79–4.46]).