Abstract

As etiologic concepts of diseases gradually changed from humoral to microbial in the 19th century, syphilis presented particularly great challenges to doctors and scientists. Was “syphilis” merely a synonym for “venereal disease,” and did all manifestations attributed to it have the same cause? The discovery in 1879 of the gonococcus by Albert L. Neisser , and of the cause of chancroid, or soft chancre, in 1890 by Augusto Ducrey , established that venereal disease and syphilis were not synonymous, but syphilis continued to mystify investigators. Symptoms could disappear for years and then—in most but not all persons—reappear with entirely different “tertiary” manifestations. ..