Theobald Smith | |
|---|---|
 | |
| Born | (1859-07-31)July 31, 1859 |
| Died | December 10, 1934(1934-12-10) (aged 75) |
| Alma mater | Cornell University,Albany Medical College |
| Known for | Texas cattle fever,Salmonella |
| Awards | Manson Medal(1932) Copley Medal(1933) |
| Scientific career | |
| Fields | Epidemiology |
| Institutions | US Department of Agriculture,Harvard University,Rockefeller University |
Theobald SmithFRS(For)[1] HFRSE (July 31, 1859 – December 10, 1934) was a pioneeringepidemiologist,bacteriologist,pathologist and professor. Smith is widely considered to be America's first internationally-significant medical research scientist.[2][3]
Smith's research work included the study ofbabesiosis (originally known asTexas cattle fever) and the more-general epidemiology of cattle diseases caused bytick borne diseases. He also described the bacteriumSalmonella enterica (formerly calledSalmonella choleraesuis), a species ofSalmonella, named for theBureau of Animal Industry chiefDaniel E. Salmon. Additional work in studying the phenomena ofanaphylaxis led to it being referred to as theTheobald Smith phenomenon.[1]
Smith taught at Columbian University (nowGeorge Washington University) and established the school's department of bacteriology, the first at a medical school in the United States.[1] He later worked atHarvard University and theRockefeller Institute.
Smith was born inAlbany, New York, the son of Philip Smith and his wife, Theresa Kexel.[4]
He received a Bachelor of Philosophy degree fromCornell University in 1881, followed by an MD fromAlbany Medical College in 1883.[2]
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 theUS Department of Agriculture (USDA) inWashington, D.C., beginning his position there in December 1883.[5]
Smith became the Inspector of the newly createdBureau of Animal Industry (BAI) in 1884. Established by Congress to combat a wide range of animal diseases—from infectious disease ofswine tobovine pneumonia,Texas cattle fever toglanders—Smith worked underDaniel E. Salmon, a veterinarian and Chief of the BAI.[6] Smith also discovered the bacterialtype species which would eventually form thegenusSalmonella. After two years of work studying the efficacy of bacterial vaccination in pigs, Smith erroneously believed he had found the causative agent of hog cholera.[7]
Smith turned his attention to Texas fever, a debilitating cattle disease; this work is detailed in a chapter inMicrobe Hunters, byPaul de Kruif. In 1889, he along with the veterinarianF.L. Kilbourne discoveredBabesia bigemina, thetick-borneprotozoanparasite responsible for Texas fever. This marked the first time that anarthropod had been definitively linked with the transmission of an infectious disease and presaged the eventual discovery of insects such asticks andmosquitoes as importantvectors in a number of diseases.
Smith also taught at Columbian University in Washington, D.C. (nowGeorge Washington University) from 1886 to 1895, establishing the school's Department ofBacteriology. In 1887, Smith began research onwater sanitation in his spare time, investigating the level offecal coliform contamination in the nearbyPotomac River. Over the next five years, Smith expanded his studies to include theHudson River and its tributaries.[8]
While Smith's work at the BAI had been highly productive, he found the rigid federal government bureaucracy stiffing and complained about the lack of leadership from his supervisor. In 1895 Smith moved toCambridge,Massachusetts to accept a dual appointment serving as professor of comparativepathology atHarvard University as well as directing the pathology lab at the Massachusetts State Board of Health.[5]
Smith joined theRockefeller Institute for Medical Research as Director of the Department of Animal Pathology in 1915 and remained there until his retirement in 1929.
He was a trustee of theCarnegie Institution from 1914 until his death in 1934.[9]
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Smith's best-known contribution was the notion, long since disproved, that there would be a “delicate equilibrium” betweenhosts andpathogens such that they would develop a "mutually benign relationship" over time.[10] This was at most aneducated guess and never became ascientific theory, but it became accepted asconventional wisdom and was even called thelaw of declining virulence. It has been disproved and replaced by thetrade-off model, which explains that eachhost–pathogen relationship must be considered separately, that there is no general pattern that predicts how all of these relationships will develop, and that there is definitely no inevitability of decreasedvirulence.[10][11]
Smith was elected to theAmerican Academy of Arts and Sciences in 1896,[12] the United StatesNational Academy of Sciences in 1908,[13] and theAmerican Philosophical Society in 1915.[14] In 1933, Smith was awarded theRoyal Society's prestigiousCopley Medal"For his original research and observation on diseases of animals and man."
{{cite book}}: CS1 maint: location missing publisher (link)The trade-off model is now widely accepted. It emphasises that each host-pathogen combination must be considered individually. There is no general evolutionary law for predicting how these relationships will pan out, and certainly no justification for evoking the inevitability of decreased virulence.
There is little or no direct evidence that virulence decreases over time. While newly emerged pathogens, such as HIV and Mers, are often highly virulent, the converse is not true. There are plenty of ancient diseases, such as tuberculosis and gonorrhoea, that are probably just as virulent today as they ever were.
