History of Medicine INTRODUCTION Tropical medicine began in the nineteenth century when doctors diagnosed infectious diseases in soldiers and colonists who had lived in tropical areas. In 1877, English scientist Sir Patrick Manson proved that mosquitoes spread elephantiasis to humans and he later theorized that the same was true with malaria. This was an enormous step in tropical medicine and the understanding of tropical diseases, leading to advances in prevention methods. The field of tropical medicine consists of the study, treatment, and prevention of tropical diseases. Tropical diseases can be defined as those that are mainly of parasitic origin and are common in tropical or subtropical areas. The climate of the tropics (between the latitudinal lines of the Tropic of Cancer (23.5N) and the Tropic of Capricorn (23.5S)) is a particularly fertile climate for these diseases because of the insects that exist there. Insects such as mosquitoes, flies, fleas, lice, and ticks are the most effective way in which these diseases are transmitted between humans, from animals to humans, and between animals. In addition to these vectors, tropical diseases that are bacterial or viral are transmitted through soil and water. Poor hygiene, crowded conditions and lack of education can add to the spread of disease in the tropics. Because of the increased distance and frequency of world travel possible today, tropical diseases are commonly seen in returning travelers, giving rise to the subcategory within tropical medicine of travel medicine to deal with maintaining the health of travelers. This guide describes the modern manuscript collections relating to tropical medicine and diseases found in the History of Medicine Division at the National Library of Medicine. A majority of the collections are dated from the nineteenth century and from the first half of the twentieth century, although there are a few collections from the eighteenth century. These collections include correspondence, printed matter and papers on specific diseases, case studies, clippings, lectures, and theses, as well as biographical information on persons involved in the study of these diseases. In addition to collections pertaining to the tropics, all collections relating to tropical medicine and tropical diseases are included (for example, cholera epidemics in the United States). Prominent sources for these collections are the Surgeon-General's Office, the Public Health Service, and the United States Army. Subjects are listed in alphabetical order with an index of terms. Alternative names appear in parentheses beside the subject in the index, as well as independently, when collections are listed that refer to this name. Brief descriptions include author of collection, physical description, and call number. Where available, the web address of the finding aid is provided. Please see the Reference Librarian for access to the collections. 23 February 2009