Abraham Horwitz, 89, director of the Pan American Health Organization for 17 years. Born in Santiago, Chile, Horwitz was elected to the directorship, the top position in the Western Hemisphere for the World Health Organization, in 1958 and became the only person to serve the agency four terms, stepping down in 1975. Since that time, he had been head of the Pan American Health and Education Foundation, where he helped launch a program to provide medical instruments and textbooks to Latin American medical students. Horwitz graduated from the University of Chile medical school in 1936 and worked on infectious diseases and public health. During a 1941 epidemic in Chile, he was one of the first to use sulfas in treating infectious meningitis. Granted a Rockefeller Foundation fellowship, Horwitz earned a master of public health degree from Johns Hopkins University in 1944 and returned to Chile as director of his university's School of Public Health. During the 1950s, he also was assistant director of standards for Chile's national health service and worked on an effort to eradicate smallpox in Chile. Known internationally for his work in nutrition--particularly the effects of vitamin A--and public health, Horwitz later served as a resident scholar at the Fogarty International Center for Advanced Study in the Health Sciences at the National Institutes of Health in Bethesda, Md. The Pan-American health group established the Abraham Horwitz Award for Inter-American Health in his honor, and the American Public Health Assn. granted Horwitz its Bronfman Prize. On Monday in Washington, D.C., of pneumonia.