Semmelweis, Ignaz Philipp, 1818-65, Hungarian physician. He was a pioneer in employing asepsis. While on the staff of the general hospital in Vienna, he recognized the infectious nature of puerperal fever and insisted that attendants in obstetrical cases thoroughly cleanse their hands; he thus greatly reduced the mortality rate from infection in childbirth. Ridicule of his belief caused him to leave Vienna (1854) for Pest, Hungary, and ultimately drove him to insanity and suicide. He recorded his results in The Cause, Concept, and Prophylaxis of Childbed Fever (1861, tr. 1941), but the value of his work was not fully recognized until c.1890.