Rocky Mountain spotted fever vaccinations, 1920s. Residents and workers being given vaccinations against Rocky Mountain spotted fever in Idaho, USA. Rocky Mountain spotted fever was a fatal disease initially identified in regions of the Rocky Mountains. Researchers at the Rocky Mountain Laboratory in Hamilton, Montana, confirmed the cause as Rickettsia bacteria transmitted by ticks. By 1924, a vaccine had been developed. Photographed in 1926 as part of work by the Rocky Mountain Laboratory.