Albert Ludwig Sigesmund Neisser (1855-1916) was a German physician, dermatologist and microbiologist. In 1877 Neisser became an assistant of the dermatologist Oskar Simon, and concentrated on sexually transmitted diseases and leprosy. During the following two years he studied and obtained experimental evidence about the causative agent (pathogen) for gonorrhea, a strain of bacteria that was named in his honor (Neisseria gonorrhoeae). Neisser was also the co-discoverer of the causative agent of leprosy with Norwegian physician Gerhard Armauer Hansen. There was some conflict between Neisser and Hansen, Hansen as discoverer of the bacillus and Neisser as identifier of it as the etiological agent, Mycobacterium leprae. In 1882 Neisser was appointed professor extraordinarius by the University at the age of 29, and worked as a dermatologist in the university hospital of Breslau. In 1898 Albert Neisser published clinical trials on serum therapy in patients with syphilis. In 1905 and 1906 Neisser travelled to Java, in order to study the possible transmission of syphilis from apes to humans. Neisser was also very active in the field of public health. He promoted preventive and educational measures to the public, and better sanitary control of prostitutes, in order to combat venereal diseases. Neisser died of septicemia in 1916, at the age of 61.