Epidemic of gastrointestinal tract infection including hemorrhagic colitisattributable to Shiga toxin 1-producing Escherichia coli O118 : H2 at a junior high school in Japan

Background. An epidemic of gastrointestinal disturbances related to food in gestion occurred at a junior high school in Komatsu, Japan, and was caused by specifically Shiga toxin (Stx) 1-producing Escherichia coli O118:H2, whi ch has not been reported previously in humans. No outbreak of E coli-produc ing Stx 1 alone had occurred. Methods. A total of 526 students and 35 adult staff members who ate the sam e food at lunch in the school were investigated. Questionnaires about food consumption at lunch were given to all 561 subjects as well as to clinics a nd hospitals that had treated 74 patients. Stool specimens from 525 subject s, and food, water, and environmentaI specimens, including cooking utensils , were collected in an attempt to identify the pathogen. Results. A total of 126 subjects (22.5%) developed a diarrheal illness. The pathogen was isolated from the stool in 131 subjects, 49 of which were asy mptomatic, and from a dipper. Salads served over several days were identifi ed as high-risk from food analysis. Gastrointestinal symptoms resembled tho se associated with previous infections of Six-producing E coil, but were mi ld. No cases of the hemolytic-uremic syndrome developed. Headache was prese nt in 87 patients. Three patients underwent surgery for acute appendicitis during this epidemic. Four of five carriers had received an antibiotic effe ctive against the pathogen. Conclusions. This outbreak of E coli O118:H2 demonstrated the clinical and epidemiologic features of infection by E coli that produces Stx 1 alone. In fections with such organisms are being recognized increasingly, and the pat tern of disease observed may differ from the pattern observed with E coli O 157:H7.