Theobald Smith: The Scientist Who Traced Texas Cattle Fever to the Tick

Who was Theobald Smith?

Theobald Smith was born in Albany, New York, in 1859, the son of a German immigrant tailor. A scholarship took him to Cornell University, where he graduated in 1881. He earned his medical degree at Albany Medical College in 1883 and returned to Cornell for graduate study, according to a biographical sketch in the medical literature.

He is often described as a physician-scientist, but his best-known work came from the livestock side of medicine. His first job, in 1884, was at the new federal Bureau of Animal Industry in Washington, where cattle diseases were the main business.

How did Smith learn bacteriology at the Bureau of Animal Industry?

The job came through a Cornell mentor, Simon Gage. Smith had no formal bacteriology training because the field was new. He taught himself from European papers and introduced Robert Koch's culture methods within a year of arriving in Washington.

At the bureau he worked under chief Daniel Salmon. He identified a bacterium linked to hog cholera that later gave the Salmonella genus its name, though the genus honors Salmon. The AVMA's profile of Daniel Salmon notes that the two also showed that sterilized cultures of dead bacteria can confer immunity.

What caused Texas cattle fever?

For decades ranchers in the North had watched cattle die after contact with herds driven up from the South, even though the Southern cattle looked healthy. Texas fever, also called splenetic or redwater fever, cut off Southern cattle from northern markets and created quarantine lines across the Plains.

Smith, working with Fred Kilborne and Cooper Curtice, showed that ticks carry the cause from one animal to the next. The biographical sketch notes that Smith is often credited alone though the work was collaborative. His 1893 monograph on the subject is regarded as a medical classic. It was the first demonstration that an arthropod could transmit an animal disease, which opened a path to understanding malaria and other insect-borne illness.

Teaching, Harvard and public health

From 1886 to 1895 Smith ran a bacteriology department at Columbian University in Washington, described as the first such department at a US medical school. In 1895 he became professor of comparative pathology at Harvard and director of the Massachusetts State Antitoxin and Vaccine Laboratory. According to the sketch, diphtheria antitoxin output rose sharply there and deaths fell.

He also described turkey blackhead, studied a parasite-transmission mechanism, and found that repeated injections can cause hypersensitivity, a phenomenon once called the Theobald Smith phenomenon.

Rockefeller Institute and later years

From 1915 until his retirement in 1929, Smith directed the Department of Animal Pathology of the Rockefeller Institute at Princeton, New Jersey. The sketch notes that he helped distinguish human and bovine tuberculosis bacilli during these years. He wrote 305 publications and received 12 honorary degrees and 11 medals, among them the Royal Society's Copley Medal.

Smith's legacy in the cattle industry

Once ticks were identified as the carriers, control shifted to dipping cattle and clearing pastures, and the tick eradication campaigns of the early twentieth century followed. Modern ranchers in the southern United States still watch the tick quarantine zone along the Texas border.

To see how the cattle trade lived with these diseases, browse farm.FM's ranching section or read a farm.FM story on Texas cattle fever. For more on his life, an Encyclopedia.com biography is a good place to start.