RISK-FACTORS FOR AND PREVENTION OF SPORADIC INFECTIONS WITH VERO CYTOTOXIN (SHIGA TOXIN) PRODUCING ESCHERICHIA-COLI O157

Background Recent outbreaks of vero cytotoxin (shiga toxin) producing Escherichia coli O157 (VTEC O157) infection have stimulated debate on food safety. However, 90% of cases in England and Wales are sporadic. We report a case-control study of sporadic VTEC O157 infection. Method s We compared 85 sporadic cases of VTEC O157 infection, identified thr ough population surveillance, with 142 controls, randomly selected fro m general practitioners' lists. We matched cases and controls for age, sex, and family doctor's practice. Exposures to foods, water, animals , farms, and environmental factors were recorded. We visited the premi ses concerned when cases had eaten beefburgers or cooked sliced meats from caterers or had had contact with a farm. Findings Consumption of a beefburger from a catering premises other than from a fast-food chai n A (a national chain) and consumption of cold cooked sliced meat leg, in a salad or sandwich) from caterers, but not butchers, was associat ed with VTEC O157 infection (odds ratios 4.63 [95% CI 1.33-30.14] and 3.36 [1.04-12.74), respectively). Policies for ensuring thorough cooki ng of burgers by one national fast-food chain differed from the other catering premises we visited. There was evidence of person-to-person s pread and transmission of VTEC O157 infection from animals. Interpreta tion Local inspection of catering establishments that serve cooked mea ts together with public education to prevent spread on farms and in ho uses would reduce the burden of VTEC O157 infection by about 10% for e ach risk factor.