Enterohemorrhagic Escherichia Coli Infection in Japanese Radish Sprouts
Enterohemorrhagic Escherichia Coli Infection
Public Health Agency of Canada
Canada Communicable Disease Report
September 1, 1997
In July 1996, an outbreak of enterohemorrhagic Escherichia coli (EHEC) infection associated with radish sprouts in school lunches was reported in Japan, during which 6,309 cases were identified, including 678 hospitalizations and three deaths. Another large-scale outbreak of EHEC infection was reported late in 1996 in Scotland associated with contaminated meat products.
Japan: In March 1997, a cluster of 96 cases of EHEC serotype O157 infection was reported in the central region (including Tokyo, Yokohama, and Nagoya); 53 cases were hospitalized and one patient died.
On investigation, the majority of the EHEC O157:H7 serotypes which were isolated from the patients and asymptomatic carriers were found to have the same pulsed-field gel electrophoresis patterns. In two of these cases, meals served at home were suspected to be the source of infection. Laboratory tests on the remaining foods in the households confirmed that white radish sprouts were the source of the EHEC O157:H7. The origin of these sprouts was a hydroponic farm in the vicinity of Yokohama. This pathogen was not isolated from any of the samples taken from the farm, which included the factory premises, water supply, packaging material, white radish sprouts, and wastewater. Investigations ruled out the possible contamination of foods during shipment and transport. An investigation is still under way on the radish seeds used to produce the sprouts.
In 1997, the Ministry of Health and Welfare in Japan launched a nationwide foodborne disease surveillance program that includes as target organisms EHEC (O157 and other serotypes), Yersinia enterocolitica O8, Campylobacter jejuni/coli, Salmonella enteritidis, and Clostridium botulinum.
United Kingdom (Scotland): Since 20 May 1997, 37 cases of EHEC infection have occurred in a nosocomial outbreak at Falkirk and District Royal Infirmary. These are all stool culture-positive cases, comprising 18 inpatients, 11 staff, and eight cases from the community. The outbreak strain has been confirmed as E. coli O157 phage type 8. Epidemiologic and environmental investigations are continuing in order to identify the source of the outbreak. Reports of laboratory-confirmed E. coli O157 infection up to 16 May 1997 were 174, compared with 32 for the same period in 1996, showing the growing importance of this foodborne pathogen.