Abstract
Purpose: :
Mass drug administration (MDA) with azithromycin in areas with endemic trachoma is part of the World Health Organization (WHO) SAFE strategy. The aim of this study was to determine the effect of two rounds of MDA with azithromycin at 6 months after the first and second annual rounds in children infected, and not infected, at baseline.
Methods: :
A longitudinal cohort of (2,516) children ages ten years and under at baseline were followed over 18 months, through two rounds of MDA (baseline and 12 months) with azithromycin provided to all members of the community. Coverage was 93%. At each survey round, a trained grader used the WHO simplified grading system to determine the presence of active trachoma. Ocular swabs were collected and shipped to the International Chlamydia Research Laboratory at Johns Hopkins University where they were analyzed by the Roche Amplicor polymerase chain reaction (PCR) for Chlamydia trachomatis infection. Rates of infection at 6 months and 18 months were compared among those with infection at baseline and among those without infection at baseline. Similar analyses were performed stratifying by age (<5 years and 5+ years).
Results: :
At baseline, 20% of children were infected. After one MDA, 20% of children with baseline infection were infected at 6 months, compared to 6% of children without baseline infection. After two rounds of MDA, the infection rate among children with infection both at baseline and 6 months was 6%. When stratified by age, 26% of children <5 years with baseline infection were infected at 6 months, compared to 13% of children 5+ years (p<.01). After two rounds of MDA, children <5 years with infection at both baseline and 6 months had an infection rate of 7%, compared to 4% in children 5+ years (p>.05).
Conclusions: :
Among children with infection at baseline, two rounds of MDA were required for the infection rate 6 month post treatment to be similar to that of children without infection at baseline. Results varied by age, suggesting shorter intervals of treatment for children <5 years should be considered.
Keywords: trachoma • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology