Objective: Vibrio cholera was extremely rare in Sichuan province(no cases in 2008). Any outbreak could indicate contamination through the food supply system. In July 2009, a hospital reported a cluster of 7 diarrhea patients;all attended the same banquet. One patient was confirmed to have Vibrio cholera (O139). We conducted this investigation to identify the source of this possible cholera outbreak.
Methods: We defined a suspect case as any banquet attendee with diarrhea (≥ 3 times/day). A confirmed case was a suspect case with a positive Vibrio cholera culture. We took stool samples or rectal swabs from all attendees for cholera culture and interviewed 272 banquet attendees about foods they ate at the banquet and kitchen workers about food preparation.
Results: 7.1% (24/337) of attendees developed cases within an average of 65 hours after eating. Three meals were served. All patients had the lunch whereas no patients only ate breakfast and/or dinner. Of 180 attendees who ate turtle meat 12% were case-patients, compared to 3.3% of 92 attendees who did not (RR = 3.6, 95%CI: 1.1 - 12). Of the 150 attendees who ate peanuts 13% were cases compared to 4.1% of 122 attendees who did not eat peanuts (RR = 3.1, 95%CI: 1.2 - 8.0). During preparation, the same utensil was used for fresh turtle meat and peanuts without washing in-between the process. Turtle meat and peanuts were stored for > 16 hours at room temperature after cooking before consumption. All 33 turtles originated from commercial production in another province.
Conclusion: This outbreak was likely caused by poor food handling of commercially produced turtles. We proposed that to improve microbiologic monitoring of aquatic food animals, and raise the awareness of good handling practices at mass gathering in rural China.