Outbreak of food poisoning due to Salmonella typhimurium DT4 in mayonnaise

Abstract

In July 1989 a large outbreak of food poisoning (68 cases) occurred at a private club in Teddington (London Borough of Richmond-upon-Thames). Initial enquiries indicated that the peak of the outbreak occurred between 20th and 26th July. An epidemiological investigation (using self-completed questionnaires) was set up to determine the probable source of infection. Two groups among those exposed were selected: club staff (129), and cricket teams playing in a club tournament (105). Response rates were 89% and 64% respectively. Overall 50% (89) had gastrointestinal symptoms, including two hospital admissions. A highly significant association was found between illness and eating sandwiches containing mayonnaise. Microbiological investigations found Salmonella typhimurium DT4 in 36 of 68 faecal samples taken. This organism is not usually associated with food poisoning outbreaks. The probable source was identified as a flock of one of the egg suppliers.