Chlamydial Infection During Trachoma Monitoring: Are The Most Difficult-to-reach Children More Likely To Be Infected?

Abstract

Purpose: : During mass antibiotic distributions for trachoma, certain individuals are difficult to locate, and go untreated. These untreated individuals may serve as a source of community re-infection, especially if they are more likely to be infected with ocular chlamydia than individuals who are easy to locate. In this scenario, intensive efforts to locate these difficult-to-reach individuals may be important for the elimination of trachoma.

Methods: : We monitored 12 Ethiopian communities 1 year after a third annual mass azithromycin treatment for trachoma. Conjunctival swabbing for chlamydial RNA was performed in a random sample of children from each community. If an insufficient number of children were enrolled during an initial monitoring day, we returned on subsequent days.

Results: : Of the 12 communities, 10 required more than 1 monitoring day. On average, 15.9% (95% CI 8.8 - 26.6) of children were enrolled after the initial day. Chlamydial infection was present in 8 communities. Of all swabbed children, 6.9% (95% CI 2.4 - 13.5) were infected with ocular chlamydia. No ocular swabs collected after the initial day were positive for chlamydial RNA. Children examined after the initial monitoring day were significantly less likely to have ocular chlamydial infection compared to children seen on the initial day; Mantel-Haenszel common OR = 0 (95% CI 0 - 0.77).

Conclusions: : In a setting of repeated annual mass azithromycin treatments, after approximately 80% of individuals have been located in a community, extra efforts to find absent individuals may not yield significantly more cases of ocular chlamydia. Therefore, the WHO recommendation of 80% antibiotic coverage is appropriate, at least in communities that have received 3 repeated mass azithromycin treatments. It is still possible that more intensive antibiotic coverage could be helpful in other settings, such as untreated communities or communities with a higher prevalence of ocular chlamydia.

Keywords: trachoma • bacterial disease • clinical (human) or epidemiologic studies: health care delivery/economics/manpower