Trachoma, an infectious eye disease caused by bacterium Chlamydia trachomatis. It is the leading infectious cause of blindness worldwide. It is a public health problem in 44 countries, and is responsible for the blindness or visual impairment of about 1.9 million people. About 142 million people live in trachoma endemic areas and are at risk of trachoma blindness. The infection is transmitted by direct or indirect transfer of eye and nose discharges of infected people, particularly young children who are the principal reservoir of infection. The disease is also spread by flies.