WIDAL, FERNAND (1862–1929), French physician, born in Algeria, where his father served as an army doctor. He studied medicine in Paris and worked there. In 1894 he was appointed associate professor, in 1911 full professor, and in 1912 he was elected member of the Academy of Sciences. He instituted a vaccination against typhoid fever in 1888. The innovation was adopted universally and it was used by all the armies that participated in World War I. In 1896 he discovered a method for the serological diagnosis of typhoid fever, which was named after him and became the prototype for the serodiagnosis of other communicable diseases. He also developed methods for diagnosing different diseases by determining the types of cells in inflammatory exudates, thus establishing the basis of cytodiagnosis. His most important contribution to pathological physiology was his recognition of the significance of chloride (in table salt) in causing edema, and he instituted a low-salt diet in cases of fluid retention in the body, which is used nowadays universally. In his research on kidney diseases, he worked on the significance of renal failure, which manifested itself in the defective ability of the body to excrete blood nitrogen. He described the various forms of jaundice, especially those caused by hemolysis, and demonstrated the fragility of red blood cells in cases of familial jaundice. He also did research work on anaphylaxis, streptococcal infections, cardiovascular diseases, and the nervous system.
S.R. Kagan, Jewish Medicine (1962), 250–1; Achard, in: Progrès médical, 44 (1929).