Introduction. In one sense Tropical Medicine is the practice of medicine in warm climates. In another sense it is the fund of information and experience accumulated by medical investigators and practitioners in the Tropics and Subtropics. To the layman and to many physicians the term “Tropical Medicine” suggests that diseases in the Tropics are essentially different in their etiology from those which are familiar to the medical profession in Temperate Zones, yet few such uniquely tropical diseases exist. Nevertheless, Tropical Medicine is in many respects quite unlike medical science and art which are taught to medical students or practiced in the United States and Europe. The differences are due primarily to the greater prevalence of certain infectious and contagious diseases in the Tropics; to the lower standards of hygiene and public health among native peoples in most warm countries; to the greater opportunities of exposure to pathogenic microorganisms; to the frequency of malnutrition, the enervating climate and the greater susceptibility of human beings to infection.