[Human genetics and infectious diseases (author's transl)].

Infectious diseases, especially the worldwide epidemic diseases such as plague, smallpox, syphilis, tuberculosis have to a great extent selective effects. This is demonstrated inter alia in the different "selection values" in the ABO blood group system. Under present day civilized living conditions O carriers have a preservation advantage over blood group A. The deletion of the selection factor "infectious disease", which entails a decline of immunity, may nevertheless regain importance if environmental changes occur.