Theobald Smith

Epidemiologist

• Born: July 31, 1859
• Birthplace: Albany, New York
• Died: December 10, 1934
• Place of death: New York, New York

American microbiologist

Considered to be the most distinguished American microbiologist and probably the leading comparative pathologist in the world, Smith made discoveries fundamental to theoretical biology, public health, and veterinary medicine, and opened new vistas in disease control.

Area of achievement Biology

Early Life

Theobald Smith’s parents, Philipp Schmitt and Theresia Kexel, emigrated from Germany following their marriage and settled in Albany, New York, where Schmitt became a tailor. Their only son was baptized in his mother’s Roman Catholic faith and given the surname of his godfather, Jacob Theobald. (He later abandoned Catholicism and became a Unitarian.) Smith’s mother, a fine musician, provided musical training for him, and his favorite recreation throughout his life was playing the piano.

Smith began his education in a German-speaking private academy; in 1872, he enrolled at the Albany Free Academy. An exceptional student, he received a state scholarship, and this, plus earnings from piano lessons and playing the chapel organ, enabled him to attend Cornell University. He was graduated with honors in 1881, enrolled in the Albany Medical College, and received the M.D. in 1883 at the top of his class.

Smith felt neither inclined nor ready to practice medicine, preferring a research career. Wealthier Americans in this situation pursued further studies in Europe and returned with a Ph.D. and a professorship in an American university. Smith, however, needed a job, and, on the recommendation of the Cornell microscopist Simon Gage, took a position with the Department of Agriculture’s Bureau of Animal Industry in Washington, D.C., established in 1884 by Congress to combat the economically devastating diseases infecting farm animals. He knew no bacteriology, very little about pathology, and nothing at all about the diseases of farm animals, but he learned in these fields by reading the papers of Louis Pasteur, Robert Koch, and other pioneers in microbiology. He taught himself the culture-plate methods of Koch and even improved on them. Thus, Smith learned bacteriology as it was quickening into an exciting new field.

On May 17, 1888, Smith married Lilian Hillyer Egleston of Washington, D.C., the daughter of a clergyman and chief of forestry in the Bureau of Forestry. It was a happy marriage; his wife supported him through the hardships and dissatisfactions that he endured during his early career. They had three children.

Smith matured into a slender, bearded man, with a long, gentle face; he was a simple, companionable, unpretentious, and guileless person, so self-effacing that, despite his achievements, he was virtually unknown to the American public.

Life’s Work

Smith quickly appreciated the significance of microbiology for the bureau’s task of finding the causes of diseases that attack farm animals. The head of the bureau, Daniel Salmon (after whom the Salmonella group of bacteria is named) assigned him to sorting out the chaos of information on swine diseases; Smith demonstrated the presence of two diseases, hog cholera and swine plague, as the major causes of death, and tracked down the microbes involved. In 1886, he disclosed that hog cholera bacterial cultures that had been killed conferred immunity, preparing the way for the development of a new type of vaccine.

Overshadowing all else during his tenure at the bureau was his six-year investigation of Texas cattle fever and the publication of the remarkable Investigations into the Nature, Causation and Prevention of Texas or Southern Cattle Fever (1893). Smith discovered that a protozoan microparasite destroyed the red blood cells of cattle. In a long series of beautifully planned experiments, he clearly described the parasite, providing the first clear demonstration of a protozoan disease in higher animals. Moreover, he was the first to trace the exact path by which an agent of disease went from one animal to another: It was transmitted to susceptible cattle by the offspring of bloodsucking ticks. The complex, meticulously verified tick-borne mechanism astounded scientists. The long-term consequences were the saving of the cattle industry by tick-eradication programs and, of greater significance, the revelation that invertebrates carry deadly germs; as a result of this discovery, over the next two decades investigators were able to demonstrate how insects and arachnids transmit the germs of malaria, yellow fever, sleeping sickness, typhus, and bubonic plague.

By the 1890’s, Smith had acquired an international reputation in science, his work having been published in German journals. There was disharmony at the bureau, however, as Salmon attempted to divert credit for Smith’s work to himself and his associates. Smith saw Salmon overgenerously make F. L. Kilborne, the superintendent of the experimental farm, coauthor of the cattle fever monograph. He chafed under the repeated injustices and waited for an opportunity to leave the bureau.

Meanwhile, Smith developed ingenious methods for culturing and differentiating microorganisms. He investigated the bacteriology of water supplies, and the American Public Health Association incorporated his techniques and studies into its Standard Methods for the Examination of Water and Waste Water (1905). Smith organized the first department of bacteriology in an American medical school at the National Medical College of Columbian University (later renamed George Washington University) and aided in the organization of the department at Cornell.

Smith’s association with the Bureau of Animal Industry ended in 1895 on the acceptance of a dual appointment in Boston as a Harvard professor in comparative pathology and director of the antitoxin laboratory of the Massachusetts State Board of Health, the nation’s first effective state health board. In Boston, Smith roamed widely with no end to his enthusiasm, investigating sewage disposal, control of water supplies, transmission of typhoid fever by milk, and many topics in host-parasite relationships.

In 1898, Smith published a classic paper differentiating human and bovine tuberculosis. Koch, the discoverer of the tubercle bacillus, believed the bacilli infecting humans and cattle were identical; Smith demonstrated their differences in virulence, structure, and growth. Two years earlier, he had met Koch in Germany and told him of his ongoing research on the two varieties. In 1901, Koch reversed his opinion and confirmed Smith’s findings but appropriated the discovery as his own, not acknowledging Smith’s priority until 1908.

Smith’s primary duty at the antitoxin laboratory was the supervision of smallpox vaccine production and the newly introduced diphtheria antitoxin. He made many improvements in vaccines, notably the use of slightly unbalanced mixtures of toxin-antitoxin for the active immunization against diphtheria. He discovered that such mixtures incite antibody production in guinea pigs and greatly enhance immunity. This prophylactic effect, once perfected for human use, was to be of enormous benefit to American children.

In 1904, Smith observed what was for many years known as the Theobald Smith phenomenon: anaphylaxis in guinea pigs. They became acutely ill when given a second injection of a toxin-antitoxin mixture several days after the first. This was the first recorded observation of hypersensitivity and the basis for the study of hypersensitivity in clinical medicine.

In 1914, Smith resigned his positions to accept the directorship of the new animal pathology laboratory of the Rockefeller Institute for Medical Research. He had been offered the directorship of the institute on its founding in 1901 but refused, not wanting to be primarily an administrator. (He was, however, on its board of scientific directors from inception to 1933 and served as its president in 1933.) The institute, needing a place outside New York City for research on animal diseases, purchased farmland near Princeton, New Jersey, with Smith largely responsible for the planning and design of the laboratories and animal quarters. With a group of young, eager scientists, the new department at first restricted itself to confirming the details of pathological and bacteriological knowledge, but it shortly became the scene of important new developments.

Smith investigated turkey blackhead, a fatal disease ruining the turkey breeding industry in the eastern states. In 1920, he found the cause to be a protozoan parasite transmitted by ingestion of embryonated eggs of a small roundworm. His work provided all the information necessary to keep turkeys healthy and, in addition, revealed an important and novel cycle of transmission and parasitism.

With a large dairy herd at his disposal, Smith studied brucellosis, the infectious abortion in cows that was responsible for losses of 20 percent in calf generation. In 1926, he induced protection by vaccination of heifers with a living, attenuated Brucella abortus culture and also found a hitherto unrecognized spiral microbe, Vibrio fetus, responsible for infection of the placentum and fetal membranes and one out of four abortions.

In 1929, the seventy-year-old scientist retired as the institute’s director while continuing to work at the laboratory. During 1934, he grew progressively weaker and died of heart failure during the administration of ether incident to an exploratory operation for intestinal cancer. At the time of his death, his peers regarded him as America’s greatest medical scientist, comparable to Pasteur and Koch. Never widely known outside scientific circles, honors came late in life. A lecture series at Princeton in 1933 led to his only book written for the lay reader, Parasitism and Disease (1934). He was recommended several times for the Nobel Prize, but, although deserving, he never received the award. Active in organizing the American Academy of Tropical Medicine and elected its first president, he did not attend its first meeting as he was stricken with the illness that led to his death. The society created the Theobald Smith Medal for notable contributions in the field. His portrait hangs at the entrance to the Theobald Smith Building of Rockefeller University in New York.

Significance

Smith summarized his own work as “a study of the causes of infectious diseases and a search for their control.” He was the first American to do important work in bacteriology and immunology, demonstrating that infectious disease could be insect-borne and that killed bacterial cultures may produce immunity, a find that was the basis for protective vaccination against several diseases. He brought attention to the hypersensitive condition and established culture methods for the bacteriological examination of milk, water, and sewage. In the development of American science, he was a major force in the professional development of bacteriology at a time when the United States was considered backward in the laboratory sciences. He brought medical science to bear on public health and its need to adapt to new findings on the sources and transmission of infectious diseases and to developments in immunology, which together resulted in a great elongation in the average life span of Americans living in the twentieth century.

Bibliography

Clark, Paul Franklin. “Theobald Smith, Student of Disease.” Journal of the History of Medicine and Allied Sciences 14 (October, 1959): 490-514. A clear, straightforward treatment of Smith’s research career.

Corner, George W. A History of the Rockefeller Institute, 1901-1953. New York: Rockefeller Institute Press, 1964. An informative account of the creation and activities of the institute; it documents Smith’s role on the board of directors and as head of the animal pathology department.

De Kruif, Paul. “Theobald Smith: Ticks and Texas Fever.” In Microbe Hunters. New York: Harcourt Brace & World, 1926. A vivid, popular, readable account of Smith’s most famous investigation. Subsequent chapters show how scientists followed Smith’s lead in investigating other insect-borne diseases.

Dolman, Claude E., and Richard J. Wolfe. Theobald Smith, Microbiologist: Suppressing the Diseases of Animals and Man. Boston: Francis Countway Library of Medicine, 2003. A detailed account of Smith’s life and career, exploring the origins of his passion for medicine, his relationships with other prominent microbiologists, and his research and contributions to livestock disease control.

Gage, Simon Henry. “Theobald Smith, Investigator and Man.” Science 84 (August 7, 1936): 117-122. A brief but perceptive essay written by Smith’s Cornell professor and lifelong friend.

Winslow, Charles-Edward Amory. “The Insect Host.” In The Conquest of Epidemic Disease. Princeton, N.J.: Princeton University Press, 1943. Less dramatic than the work by De Kruif but beautifully written, instructive, and rich in interpretation and insights.

Zinsser, Hans. “Biographical Memoir of Theobald Smith.” Biographical Memoirs. National Academy of Sciences 17 (1937): 261-303. This is the best study of Smith. Includes a bibliography of 247 of his publications.