Investigation of Food outbreak, Pataew village Moo 5, Don Pao, Mae Wang District, Chiang Mai Province, May 3-6, 2009

Abstract

             The objectives of outbreak investigation of food poisoning at Moo 5 Pataew village, Don Pao subdistrict, Macwang district, Chiang Mai were: To verify diagnosis and confirm existence of the outbreak, including demographical study of the epidemic, and to find the risk factors related to the outbreak for control measures. Methods: Descriptive study and case-control analytical study were performed. Stool from patients, cookers, servers and swabs from kitchen utensil were collected and cultured to find the organism that causes the outbreak. The process of cooking was interviewed.

Finding: Among the participants who joined the wedding ceremony on April 2^nd, 142 cases were found, 59.2 % of cases were female. The age of cases ranged from 2-79 years, mean age was 44.5 years. The highest symptoms were acute diarrhea, abdominal pain, nausea, vomiting, headache, and fever, respectively. The pattern of epidemic curve was shown to be common source outbreak. The index case was detected at 7.00 pm that night while the last case got sick on April 4^th, at 6.45 pm. The median of incubation period was 13.6 hours. The cases were distributed around the whole village and nearby district. The most cases were found at Moo 5 (46 cases) with the attack rate of 8,712/100,000 population. The suspected food was egg fried rice that made for the dinner. The cases tended to eat egg fried rice higher than control (95 % confidence interval 11.2<OR<2221.2; p-value < 0.001). Salmonella group E was found in 7 cases, 3 cookers, I server, and 2 chopping blocks. All food served in that dinner was thrown before collecting.

This outbreak represented food poisoning through contamination from food handlers, like others investigation the food was kept for a long time before serving. Active case finding was performed, suspected cases and contact cases were collected and treated. The active surveillance was performed and no more case was found.