Trachoma Infection in Children Predicts Infection in the Rest of the Community

Abstract

Abstract: : Purpose:The WHO has recommended mass azithromycin administration in an attempt to eliminate the ocular chlamydia that causes trachoma. They suggest following children to monitor infection in the entire community, as this group is most likely to become repeatedly infected with trachoma. However, this does not reveal the infectious burden in the rest of the community. Here we report the prevalence of infection in different age groups in treated versus untreated villages, and assess whether children are a reasonable sentinel group; specifically, we estimate the correlation of prevalence of infection in children with that of the rest of the community. Methods: Six villages were randomly chosen from a sub–district of the Gurage Zone in Ethiopia. In the spring of 2003, all eligible individuals in 3 of the 6 villages were offered a single dose of oral azithromycin. 12 months later, all 6 villages were sampled and treated. Right upper conjunctival swabs were obtained from all individuals aged 1–5 years and a sample of individuals over the age of 5 years. Samples were assayed for chlamydial DNA using Amplicor PCR. Results: 417 children 1 to 5 years and 491 individuals older than 5 years were sampled from the 6 communities. In the 3 untreated villages, the average prevalence of infection in those aged 1 to 5 years was 34.2%. For the same age group in the 3 treated villages, the average prevalence was 13.3%. For those over 5 years in untreated villages the average prevalence was 14.1%. In the same age group in treated villages, the average prevalence was 1.3%. The correlation between the prevalence of infection in those under 1 to 5 years and those older than 5 years was r = 0.87, p=0.02 (r=0.89 in pre–treatment villages, and r=0.89 in post–treatment villages). Age–prevalence curves were constructed to detail the distribution of infections both before and after treatment. Conclusions: It has long been known that children bear much of the burden of infection both before and after mass antibiotic treatment. Here we demonstrate that the prevalence of infection in pre–school children is an excellent predictor of infection in the entire community, both before and after treatment.

Keywords: trachoma • antibiotics/antifungals/antiparasitics • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled