Trachoma is the world's leading cause of preventable blindness. This disease, caused by Chlamydia trachomatis, is endemic in many parts of the developing world. In 1990s we evaluated the use of community-wide treatment with oral azithromycin in a project called Azithromycin in Control of Trachoma (ACT). This approach resulted in clinical improvement and dramatic reduction in prevalence of chlamydial infection through a 1-year follow-up. We enrolled the ACT villages, as well as an additional village that had not had any prior treatments, in our ACT II (2005) study and performed clinical surveys to assess trachoma activity testing conjunctival swabs for the presence of C. trachomatis by nucleic acid amplification tests (NAATs). Thus, we hoped to determine the long-term (10 year) effects of azithromycin treatment.