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Intestinal infections in Germany due to enterohemorrhagic E. coli bacteria (EHEC) between 1998 and 2001 reveal a large scale of biological diversity of their pathogens. However, no dramatic increase of their clinical importance and public health implications has been observed. As strains of serovar O157:H7 have continuously declined as causative agents, other serovars such as O26:H11 and O103:H2 have replaced them. The great diversity of the EHEC pathogens might point to a great number of various infection routes and sources. Since recently new pathogenic factors of EHEC bacteria have been detected (especially by the sequencing of the genome of EHEC), it is currently not possible to define a clear-cut difference between human pathogens and nonhuman pathogens. The enhanced surveillance of EHEC pathogens with respect to their biological diversity and dynamics, their epidemic spread, and their infection routes and sources remain an essential task of the public health authorities.