TROPICAL MEDICINE

medical science applied to diseases that occur primarily in countries with tropical or subtropical climates. Tropical medicine arose during the 19th century when physicians charged with the medical care of colonists and soldiers first encountered infectious diseases unknown in the temperate European climate. Several major advances in the control of tropical diseases occurred in the last quarter of the 19th century. Sir Patrick Manson showed that the parasite that caused filariasis was transmitted by mosquito bites. Other tropical diseases were also soon shown to be spread by mosquitoes, including malaria in 1898 and yellow fever in 1900. Within a few years the role of the tsetse fly in transmitting sleeping sickness, the sand fly in kala-azar, the rat flea in plague, the body louse in epidemic typhus, and the snail in spreading schistosomiasis were also discovered. Most early efforts to control tropical diseases involved such measures as the rigorous draining of swamps and other mosquito-breeding areas. These and other environmental measures continue to be among the most effective available, although the introduction of new antibiotics has also had an impact on some common tropical diseases. The destructive social and economic effects of tropical diseases soon caused the research emphasis to shift from clinical practitioners in the tropics to organized research institutes in Britain and other colonizing countries. National and international commissions were organized by the colonial powers to eradicate plague, malaria, cholera, yellow fever, and other common tropical conditions, at least from areas in which Europeans lived and worked. The first schools devoted to the study of tropical medicine were founded in England in 1899, and many others soon followed. Following the achievement of independence by most former colonies in the 1960s, those nations' independent governments took over most research and prevention efforts, though continuing to receive help from the World Health Organization and from their mother countries as well.