1. From the Dana Center for Preventive Ophthalmology and
2. Kongwa Trachoma Project, Kongwa, Tanzania;
3. the Division of Infectious Diseases, Department of Medicine, Johns Hopkins University, Baltimore, Maryland;
4. the Division of Infectious Diseases, Department of Medicine, Johns Hopkins University, Baltimore, Maryland; 4Division of Intramural Research of the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland.