ASS ANTIMICROBIAL ADministrations have been used in several control programs and have been contemplated for many others. They have proven to be effective against some parasitic diseases (eg, onchocerciasis and filariasis), but at times have not lived up to expectations (eg, malaria). 1-3 Various forms of mass treatment have been used for bacterial diseases, including sexually transmitted chlamydia and syphilis. 4,5 The World Health Organization (WHO) 6 and its partners are now using repeated mass azithromycin administrations to control the ocular strains of chlamydia that cause trachoma, the world's leading cause of infectious blindness. 7 Trachoma meets the critical criteria for eradicability: there is an effective treatment for the ocular strains of Chlamydia trachomatis, and there is no known animal reservoir. Cur

Ocular chlamydial infection was not eliminated in children aged 1 to 5 years after a single mass azithromycin distribution; it slowly returned over 24 months, although not to baseline levels. Repeated treatments or other effective measures will be necessary for elimination.

BackgroundAntibiotics are a major tool in the WHO's trachoma control program. Even a single mass distribution reduces the prevalence of the ocular chlamydia that causes trachoma. Unfortunately, infection returns after a single treatment, at least in severely affected areas. Here, we test whether additional scheduled treatments further reduce infection, and whether infection returns after distributions are discontinued.MethodsSixteen communities in Ethiopia were randomly selected. Ocular chlamydial infection in 1- to 5-year-old children was monitored over four biannual azithromycin distributions and for 24 months after the last treatment.FindingsThe average prevalence of infection in 1- to 5-year-old children was reduced from 63.5% pre-treatment to 11.5% six months after the first distribution (P<0.0001). It further decreased to 2.6% six months after the fourth and final treatment (P = 0.0004). In the next 18 months, infection returned to 25.2%, a significant increase from six months after the last treatment (P = 0.008), but still far lower than baseline (P<0.0001). Although the prevalence of infection in any particular village fluctuated, the mean prevalence of the 16 villages steadily decreased with each treatment and steadily returned after treatments were discontinued.ConclusionIn some of the most severely affected communities ever studied, we demonstrate that repeated mass oral azithromycin distributions progressively reduce ocular chlamydial infection in a community, as long as these distributions are given frequently enough and at a high enough coverage. However, infection returns into the communities after the last treatment. Sustainable changes or complete local elimination of infection will be necessary.Trial RegistrationClinicalTrials.gov NCT00221364

The common wisdom is that a trachoma program cannot eliminate ocular chlamydia from a community, just reduce infection to a level where there would be minimal blindness. We describe the success of multiple mass antibiotic treatments, demonstrating that complete elimination of infection may be an attainable goal in an area with modest disease.