It was Dr. Howard T. Ricketts who confirmed Chowning and Wilson’s theory about ticks being carriers of RMSF. A pathology professor at the University of Chicago, he set up an experimental station at the Northern Pacific Hospital in Missoula, Montana, in 1906, where he did microscopic studies on samples from people with RMSF. He also conducted the animal studies necessary to see how RMSF was spread.
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Dr. Howard Ricketts stands in a store doorway behind members of the Montana State Medical Society. Ricketts spoke at the May 1906 meeting of the society to urge the State of Montana to appropriate sufficient funds to continue his study of Rocky Mountain spotted fever.
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Image: Office of NIH History and Stetten Museum, 1537
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Ricketts proved that ticks transmitted RMSF from animals to humans by placing ticks on infected guinea pigs and then moving the tick to healthy guinea pigs, who then got ill. He also identified the bacteria that causes RMSF in the blood of infected animals and in ticks and their eggs; that bacteria are now called Rickettsia rickettsii in his honor. A whole group, or genus, of very small bacteria that cause diseases in humans after insect bites is called Rickettsia, and the diseases they cause are called Rickettsial diseases, in his honor. As Ricketts was winding up his RMSF studies, he went to Mexico to study typhus; he died there of typhus in 1909.
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Dr. Howard Ricketts stands in a store doorway behind members of the Montana State Medical Society. Ricketts spoke at the May 1906 meeting of the society to urge the State of Montana to appropriate sufficient funds to continue his study of Rocky Mountain spotted fever.
The interior of the tent laboratory that Dr. Howard Ricketts set up on the grounds of the Northern Pacific Hospital in Missoula, Montana, to study Rocky Mountain spotted fever in 1906.
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Image: Office of NIH History and Stetten Museum, 1537 and 1535
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Once it was known that people got RMSF by being bitten by infected ticks, the efforts to control ticks increased. Dr. Robert Cooley, the Montana State Entomologist, directed these efforts from 1917-1922. He also collected as many species of ticks as he could, building a huge reference collection for future researchers. He studied the ticks’ development from egg to adult to gain an understanding of how and when the ticks themselves got infected. He moved to the Canyon Creek Schoolhouse laboratory when it opened in 1921 as head entomologist.
These cattle are being “dipped” in disinfectant in an effort to kill ticks. Dr. Robert Cooley suggested that people might come into contact with ticks through their cattle and other livestock so that killing the ticks on livestock would reduce the number of people who got ill.
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Image: Office of NIH History and Stetten Museum, 1520
