Karl Friedrich Meyer, son of Theodor Meyer and his wife Sophie, born Lichtenhahn, was an outstanding bacteriologist, experimental pathologist, virologist, epidemiologist and ecologist, and an inspiring teacher. He studied at the universities of Basel, Zuerich, Munich and Bern and was awarded the degree Dr.Med.Vet. by the University of Zuerich in 1908, although the research for his thesis was carried out in Bern under Professor W. Kolle*. In October 1908 he arrived in Pretoria at the Veterinary Research Institute, then in the process of moving to Onderstepoort, where he took charge of the pathology laboratory. Though he remained in South Africa for only two years he published five scientific reports during this short period, all of them in the Report of the Government Veterinary Bacteriologist of the Transvaal for 1908/9 and 1909/10. These dealt with his experimental studies on a specific purulent nephritis in horses, experimental and epidemiological observations and the pathology of contagious pleuropneumonia, the nature of Koch's bodies and their role in the pathogenesis of East Coast Fever, the chemotherapeutic treatment of biliary fever in dogs, and the complement fixation test in the diagnosis of glanders.
Differences with the institute's director, Arnold Theiler* - both had dominant personalities - led Meyer to leave Onderstepoort in May 1910 to accept a post as assistant professor of pathology and bacteriology at the School of Veterinary Medicine, University of Pennsylvania. In 1913 he went to the University of California as professor of bacteriology and experimental pathology. He was associated with the university's George Williams Hooper Foundation for Medical Research in San Francisco, became its director in 1924, and remained there until his retirement in 1954. In 1924 he presented a thesis for the degree Dr.Phil. at the University of Zuerich on The bacterial symbiosis in the concretion deposits of certain operculate land molluscs of the families Cyclostomatidae and Annulariidae.
Meyer made a life-long study of the diseases of animals transmissible to humans. From 1926 he turned his attention to plague and demonstrated that sylvatic plague persisted in numerous wild rodent species as reservoirs. By the early 1930's he was considered the leading authority on botulism. During World War II (1939-1945) he developed a plague vaccine as one of his outstanding contributions to medicine. He also made contributions to the control of ornithosis and encephalitis, and participated in research on tropical diseases, mussel poisoning, dental caries, and hearing impairment. This work resulted in a total of over 300 publications, including Fifty years of botulism in the United States and Canada (1950, with B. Eddie). Many honours were bestowed upon him and he played an active role in many scientific societies. Throughout his career he retained close links with South Africa and in March 1963 visited Onderstepoort again.
Meyer was married to Mary Elizabeth Lindsay, with whom he had a daughter. After her death in 1958 he married Marion Lewis in 1960.