Discrepancy Between Active Trachoma and Tests of Chlamydial Infection in Alto Amazonas, Peru

Trachoma mapping in Latin America is incomplete, especially in indigenous communities of the Amazon thought to be at highest risk. The aim of this study was to determine the prevalence of clinical, microbiological, and serologic evidence of trachoma in a remote area of the Peruvian Amazon.

A population-based sample of households from rural communities in Alto Amazonas province was selected using 2-stage cluster sampling. In children aged 1-9 years, conjunctival photographs, conjunctival swabs, and dried blood spots were collected. Photographs were graded for trachomatous inflammation-follicular (TF). Swabs were processed for Chlamydia trachomatis with a nucleic acid amplification test. Dried blood spots were assessed for antibody responses to C. trachomatis with a multiplex bead assay.

A total of 778 children aged 1-9 years from 21 communities participated. The age-adjusted prevalence of TF among 1-9-year-old children was 25.4% (95% CI 21.3%-29.5%), compared with 0.8% (95% CI 0.5%-1.0%) for ocular C. trachomatis and 6.6% (95% CI 4.5%-9.0%) for Pgp3-specific antibodies to C. trachomatis.

This region of the Peruvian Amazon had a high burden of clinical trachoma but low levels of C. trachomatis ocular infection and seropositivity.