Theobald Smith FRS(For) HFRSE (July 31, 1859 – December 10, 1934) was a pioneering epidemiologist, bacteriologist, pathologist and professor. Smith is widely considered to be America's first internationally-significant medical research scientist. Smith's research work included the study of babesiosis (originally known as Texas cattle fever) and the more-general epidemiology of cattle diseases caused by tick borne diseases. He also described the bacterium Salmonella enterica (formerly called Salmonella choleraesuis), a species of Salmonella, named for the Bureau of Animal Industry chief Daniel E. Salmon. Additional work in studying the phenomena of anaphylaxis led to it being referred to as the Theobald Smith phenomenon. Smith's contribution that is well known even by many laypeople is called the "law of declining virulence". This is based on his disproved notion that there is a “delicate equilibrium” between host and pathogen and that they develop a "mutually benign relationship" over time. This was at most an educated guess (in other words a hypothesis) and never became a scientific theory, but it became accepted as conventional wisdom and was even called the "law of declining virulence". It has been disproved and replaced by the trade-off model, which explains that each host-pathogen relationship must be considered separately and that there is no general pattern that predicts how each of these relationships will develop, and definitely no inevitability of decreased virulence. Smith taught at Columbian University (now George Washington University) and established the school's department of bacteriology, the first at a medical school in the United States. He later worked at Harvard University and the Rockefeller Institute. He was a trustee of the Carnegie Institution from 1914 until his death in 1934. Education Smith was born in Albany, New York, the son of Philip Smith and his wife, Theresa Kexel. He received a Bachelor of Philosophy degree from Cornell University in 1881, followed by an MD from Albany Medical College in 1883. After his graduation from medical school, Smith held a variety of temporary positions which might broadly be considered under the modern heading of "medical laboratory technician". After some prodding by his former professors, Smith secured a new research lab assistant position with the Veterinary Division of the US Department of Agriculture (USDA) in Washington, D.C., beginning his position there in December 1883. Research Smith became the Inspector of the newly created Bureau of Animal Industry (BAI) in 1884. Established by Congress to combat a wide range