The primary objective of the study is to determine optimal, cost-effective strategies for elimination of blinding trachoma and infection under differing mass treatment coverages and frequencies in areas of different endemicities: hypoendemic Gambia, mesoendemic Tanzania, and hyperendemic Niger. The major activities to meet this objective are

(1) conduct clinical trials of different levels of antibiotic coverage and frequency in three countries;

(2) determine the optimal cost-effective strategy for mass antibiotic treatment;

(3) model the trajectory of decline in trachoma and ocular C. trachomatis infection under optimal program specifications.