Wassermann, August von, WAH suhr muhn or VAHS uhr mahn, OW goost fuhn (1866-1925), was a German bacteriologist and immunologist. He became well known for the development of an important blood test used to diagnose syphilis called the Wassermann test. The test, announced in 1906, became a model for later research on blood tests to determine the presence of antibodies to viruses and other disease agents. Today, the Wassermann test has been largely replaced by other tests for syphilis.