Unusual outbreak of food poisoning

On August 25 1990, over 400 people who attended a Thailand handicappeds' sport day at a provincial physical education college developed gastrointestinal symptoms after having dinner. An epidemiological team want to determine causes(s) and recommend how to prevent and control a food poisoning outbreak. The investigation included interviewing all 1,210 persons who attended the sport's day. In addition, an environmental survey, laboratory analysis of food samples, and rectal, ear, throat and nasal swabs from foodhandlers were also performed. A case was defined as a person who ate any items of dinner food and experienced vomiting, nausea, abdominal pain, and diarrhea. There were 485 cases out of 1,094 persons, an attack rate of 43%. Interviews were completed for 470 out of 485 cases. The three most common symptoms were nausea (93%), vomiting (88%), and abdominal pain (81.5). The mean incubation period was 3.20 hours. Three out of four items of food had a significant association with illness. Among these 3 items, eclairs had to the highest crude relative risk, 7.0 (95% CI = 4.8, 10.2). For statistical analysis, logistic regression by unconditional method was used, and found that only eclairs which were prepared during the night before the dinner and kept at room temperature for at least 12 hours before serving, remained statistically significant in the model (RR = 11.96; 95% CI = 9-22). Laboratory examination of foods and foodhandlers indicated heavy growth of Staphylococcus aureus producing toxins A and C and Bacillus cereus in eclairs. Culture of nasal swabs from healthy foodhandlers identified B. cereus and S. aureus of different phage types from those in eclairs.(ABSTRACT TRUNCATED AT 250 WORDS