Roux, Pierre Paul Émile (1853–1933), a French bacteriologist. He studied medicine at the University of Paris and worked there as a clinical aide, 1874–78. From 1878 to 1888 Roux worked with Louis Pasteur. He helped produce vaccines for anthrax and hydrophobia, and studied the causes of cholera. In 1880, with Edmond Nocard, he discovered the pneumonia microbe. Roux was an assistant in the Pasteur Institute, 1888–1904, and its director, 1904–18, working on vaccines for diphtheria, syphilis, and tetanus. He was a pioneer in the study of viruses.