Fig. 16. Disease mapping, using trachoma prevalence in administrative units as an example. A. Missouri, United States, 1937. (Reproduced by permission of Oxford University Press [Julianelle LA: The Etiology of Trachoma, p iv. New York, The Commonwealth Fund, 1938].) B. Hungary, 1939. ( Grósz E: A Trachoma, p 55. Budapest, Királyi Magyar Egyetimi Nyomda, 1940.) C. Nepal, 1979-1980. (Brilliant LB, Pokhrel RP, Grasset NC, et al: Epidemiology of blindness in Nepal. Bull WHO 63:375, 1985.) Australia, 1976-1979. (Reproduced with permission of The National Trachoma and Eye Health Program of the Royal Australian College of Ophthalmologists, p 40 and p 46. Sydney, Royal Australian College of Ophthalmologists, 1980)