Theobald Smith (July 31, 1859 - December 10, 1934) was a pioneering epidemiologist and pathologist and is widely-considered to be America's first internationally-significant medical research scientist. After his graduation from medical school, Smith held a variety of temporary positions as a medical laboratory technician. Smith became the Inspector of the newly created Bureau of Animal Industry (BAI) in 1884 to combat a wide range of animal diseases. In 1889, he discovered Babesia bigemina, the tick-borne protozoan parasite responsible for Texas fever. This was the first time an arthropod had been linked with the transmission of an infectious disease and presaged the eventual discovery of insects as important vectors in a number of diseases (see yellow fever, malaria). Smith also discovered the bacterial species which would eventually form the genus Salmonella. In 1895 he observed differences between human and bovine tuberculosis. In 1899 he discussed the possibility of mosquitos as a malaria transmission vector. In 1903 he discovered anaphylaxis and in 1909 he used toxin/antitoxin as a vaccine for diphtheria. Smith joined the Rockefeller Institute for Medical Research as Director of the Department of Animal Pathology in 1915 and remained there until his retirement in 1929. He died in 1934 at the age of 75.