A cooperative study of sarcoidosis in Asia and Africa: analytic epidemiology.

The characteristics of about 2,000 Japanese sarcoidosis cases collected by the Japan Sarcoidosis Committee during the 10-yr period, 1963-1972, were chronological increase with decreasing infectious diseases (represented by tuberculosis), north-to-south decline in sarcoidosis incidence in accordance with the Oxford Atlas Seasonal Climates, the age of cases shifting to the younger group in areas of high incidence, a local outbreak, and familial aggreagations. These results led the authors to an hypothesis that sarcoidosis is a disease induced by an infective agent or agents, prevalent in cold places, becoming influential in association with ecological changes, and affecting persons with predispositions.