[1] Wassermann developed a complement fixation test for the diagnosis of syphilis in 1906, just one year after the causative organism, Spirochaeta pallida, had been identified by Fritz Schaudinn and Erich Hoffmann.

[2] The so-called "Wassermann test" allowed for early detection of the disease (despite its nonspecific symptoms), and thus prevention of transmission.

He attributed the development of the test to earlier findings of Jules Bordet and Octave Gengou (complement fixation reaction) and to a hypothesis introduced by Paul Ehrlich in his interpretation of antibody formation.

[1] The Wassermann test remains a staple of syphilis detection and prevention in some areas, although it has often been replaced by more modern alternatives.

[2] With Wilhelm Kolle, he published the six-volume Handbuch der Pathogenen Mikroorganismen (Handbook of Pathogenic Microorganisms).