Trachoma is a virulent form of conjunctivitis caused by Chlamydia trachomatis, a bacterial organism transmitted by flies that crawl into the eyes of small children. Direct transmission of the organism from fingers, damp towels, and other objects also occurs. Characteristically, reinfection is frequent in endemic regions; this leads to severe scarring and contractures, especially of the upper eyelid, and also causes blood vessels to invade the cornea, rendering it opaque. These effects of recurrent infection make trachoma a leading cause of blindness in those parts of the world where the condition is prevalent. These are predominantly poor, rural areas in hot, dry countries such as some nations in the Middle East and in arid regions of North Africa, India, Pakistan, and inland Australia.
Trachoma is responsible for about 6 million out of a total of 20 million cases of blindness worldwide, and it causes impaired vision in about 140 million people. Determined efforts have greatly reduced the incidence of new cases in the last two decades of the twentieth century, however. It is rare in industrially developed nations with good hygiene and effective fly control measures—such as screened windows. Trachoma is an exclusively human infection, so if vulnerable populations can be protected from exposure (e.g., if flies can be reduced or eliminated), transmission will cease and the infection can be prevented. These tactics have worked well in many regions, including among Australian Aborigines, where the prevalence was very high until control programs were established.
Control was achieved in Australia by an aggressive campaign led by Dr. Ida Mann, who devoted her life to this cause. Her methods comprised topical application of antiseptic and antibiotic eyedrops, disinfection and face washing, education about personal hygiene, and fly control programs. Initially this was a mass campaign, and it was reduced to individual case management as endemic conjunctivitis was brought under control. The same tactics have worked in the Middle East (e.g., among nomadic Bedouin populations in Saudi Arabia), and they are working well in endemic regions of India and Pakistan. The World Health Organization, with strong support from several foundations and nongovernmental organizations devoted to prevention of blindness, aspires to eliminate trachoma by 2020.
JOHN M. LAST
(SEE ALSO: Vision Disorders)