rickettsemia

Rick·etts \ˈrik-əts\ , Howard Taylor (1871–1910), American pathologist. Ricketts is remembered for his discovery of the causative organisms and mode of transmission of Rocky Mountain spotted fever and typhus. He began studying Rocky Mountain spotted fever in 1906. He showed that the disease could be transmitted to a healthy animal by the bite of a certain tick. Two years later he described the causative microorganism. He had discovered it in the blood of the infected animals as well as in the ticks and their eggs. In 1909 he went to Mexico to study typhus. He found that the kind of typhus he was studying was transmitted by the body louse, and he was able to locate the disease-causing organism in the blood of the victim and in the lice. He went on to demonstrate that the disease could be transmitted to monkeys, who, after they had recovered, would develop immunity to the disease. His work on immunity and sera became the basis for further advancement in vaccines.