Skip to main content Skip to Search Box
Summary Article: Theobald Smith
from Encyclopedia of Life Sciences

(1859-1934) American bacteriologist, known particularly for his contributions towards the study of tuberculosis and the tick transmission of Texas fever in cattle.


Texas fever


bovine TB

hog cholera


Born in Albany, New York, the only son of recent immigrants from Germany, Smith on graduation from a local school won a state scholarship to Cornell University, where he showed increasing interest and ability in studies of biology and mathematics. This led him back to medical school in Albany, where during the two-year course he was able to spend one semester in the biological laboratories at Johns Hopkins. It was an eye-opener for the young Smith: he decided on a life in research rather than medical practice. He returned to Cornell for graduate work in biology; but very soon, at the age of 25, he was offered the chance to become Director of the Pathology Laboratory of the Bureau of Animal Industry, working under D. E. Salmon. He spent eleven very productive years there, cementing his interest in comparative studies with work on human and bovine tuberculosis. Like John McFadyean in London, he challenged Robert Koch's authoritative views, and continued to explore differences in mammalian tubercle bacilli, and consequent problems associated with vaccination procedures, to the end of his life. See also Koch, Heinrich Hermann Robert, Tuberculosis, and Vaccination

Smith's earliest notable results were obtained when, on arrival at the US Bureau of Animal Industry (USBAI), he was presented with the problem of 'hog cholera' - a problem that neither he, nor Koch, Louis Pasteur or Elie Metchnikoff succeeded in solving before E. A. de Schweinitz and Marion Dorset in 1903 showed the disease to be transmitted by bacteria-free filtrates - i.e. a virus disease - and the 'hog cholera bacillus' so carefully studied by Smith and others to be merely a secondary invader. See also Pasteur, Louis, and Metchnikoff, Elie (Ilya)

Propelled so suddenly into the study of animal diseases, and fully occupied in the pathology laboratory, Smith never had the opportunity - or the funds - to spend time in European universities as was almost obligatory for his American contemporaries at the time. But with his solid European family background he read French and German fluently, and so could glean the information he needed from European language journals; and he himself published a number of papers in German journals.

Smith's crowning achievement during his time at the USBAI in the 1880s was the seminal study with which his name will always be linked: the demonstration that Texas cattle fever is caused by a protozoan parasite which he named Piroplasma bigeminum, now known as Babesia bigemina, transmitted by ticks - unlike the filaria of elephantiasis, earlier shown by Patrick Manson to be transmitted by Culex mosquitoes. Smith, working with cattle, could carry out crucial transmission experiments which had been unthinkable for Manson working with a human disease. See also Protozoa, and Manson, Patrick

In 1895 Smith was called to Harvard, appointed the first George Fabyan Professor of Comparative Pathology, and also Director of the antitoxin laboratory of the Massachusetts State Board of Health. He stayed at Harvard until 1914, when he was invited to head a newly established department of animal pathology at Princeton, New Jersey, of the Rockefeller Institute, where he stayed until retirement in 1929.

Further Reading
  • Smith, T (1934) Parasitism and Disease. Princeton: Princeton University Press.
  • Gillispie, CC (ed.) (1970-1980) Dictionary of Scientific Biography. New York: Charles Scribner's Sons.
  • Lise Wilkinson
    Wellcome Institute for the History of MedicineLondon, UK
    Wiley ©2007

    Related Articles

    Full text Article Smith, Theobald (1859 - 1934)
    The Cambridge Dictionary of Scientists

    Smith graduated in medicine in 1883; he chose not to enter medical practice but to move into veterinary work in the new US...

    See more from Credo