Tropical medicine is interdisciplinary branch of medicine that deals with health issues that occur uniquely, are more widespread, or are more difficult to control in tropical and subtropical regions. Physicians in this field diagnose and treat a variety of diseases and ailments. Most infections they deal with are endemic to the tropics. A few of the most well-known include malaria, HIV/AIDS, and tuberculosis. They must be knowledgeable in the 18 lesser known neglected tropical diseases, which include Chagas disease, rabies, and dengue. Poor living conditions in underdeveloped tropical countries have led to a rising number of non-communicable diseases. These diseases include cancer and cardiovascular disease, which, in the past, have been more of a worry in developed countries. Physicians trained in tropical medicine must also be prepared to diagnose and treat these diseases. Training for physicians wishing to specialize in tropical medicine varies widely over the different countries. They must study epidemiology, virology, parasitological, and statistics, as well as the training required of an ordinary MD. Research on tropical diseases and how to treat them comes from both field research and research centers, including those of the military. Sir Patrick Manson is recognized as the father of tropical medicine. He founded the London School of Hygiene & Tropical Medicine in 1899. He is credited with discovering the vector by which elephantiasis was being passed to humans. He learned it was a microscopic nematode worm called filaria sanguinis hominis. He continued to study this worm and its life cycle and determined the worms underwent metamorphosis within female culex fatigans mosquitoes. Thus he discovered mosquitoes as a vector for elephantiasis. After this discovery he collaborated with Ronald Ross to examine the transmission of malaria via mosquito vector. His work with discovering vectors as modes of transmission was