Chief Medical Officer, Section of Control of Trypanosomiases & Leishmaniases, World Health Organization since 1990. Secretary, Steering Committee(s) on Chagas Disease, Special Programme on Research and Training in Tropical Diseases, World Health Organization, Geneva, 1979-1990. Advisor in Epidemiology for Argentina, Chile, Paraguay & Uruguay, Pan-American Health Organization, Argentina, 1977-1979.
Chief, Epidemiological Analysis, Ministry of Health, Colombia, 1972-1977. Associate Proofessor of Epidemiology, National School of Public Health, Colombia, 1973-1977.