Molecular epidemiological investigation of enterohaemorrhagic Escherichia coli isolates in Japan.

We have established several measures for control and prevention of EHEC infection including designation of the disease as notifiable since there was the sudden increase in the incidence of infection with EHEC O157:H7 in Japan in 1996, involving multiple outbreaks. Improvements in methodologies for isolation of these organisms and enhanced laboratory screening have revealed a variety of sources in food and animals. Although there seems to be a bovine reservoir for O157 EHEC in Japan as well as North America and UK, different foods have been linked to EHEC infection including salads, radish sprouts and salmon roe. There is clear evidence that divergent clones of EHEC O157:H7 are prevalent throughout Japan based on laboratory surveillance, however, we still need to better define the role of EHEC serogroups other than Escherichia coli O157 as important causes of human infection.