Trachoma is one of the oldest known human diseases. It was described in ancient Egyptian and Chinese writings. Once common throughout the world, it is now a major problem only in certain developing countries. 1 In the 19th century trachoma was endemic in much of western Europe and the U.S. It disappeared with improved standards of living and hygienic conditions, rather than as a result of antitrachoma programs. Trachoma is a disease of poverty and it is most important in areas where environmental sanitation and personal hygiene are poor. Today it is the world’s leading preventable cause of blindness, with over 600 million people affected and millions blinded. Parts of the world where trachoma is a particularly large-scale problem include northern and southern subSaharan Africa and parts of Southeast Asia.