Food poisoning outbreak investigation of Salmonella Enteritidis in a village of Ponenakaew District, Sakhon Nakorn Province, February 2018

Abstract

Background: On 21 February 2018, Sakhon Nakorn Provincial Health Office was notified of several patients with diarrhea, abdominal pain, nausea and vomiting. An investigation was conducted during 21–28 February 2018 to confirm diagnosis and outbreak, determine epidemiologic characteristics, identify source and mode of transmission, and recommend preventive and control measures.
Methods: Medical records of these patients were reviewed. Active case finding was carried out in the affected community for early detection and treatment. Samples for laboratory diagnosis included rectal swabs and stool specimens from 5 cases, suspected water and foods. A retrospective cohort study was performed to determine risk factors. An environmental investigation was conducted in the affected community.
Results: A total of 18 food poisoning cases were detected. All the cases reported consumption of foods made from veal and organs of the calf. The attack rate among 49 villagers with exposure to these foods was 36.7% (18/49). The most common clinical feature was diarrhea (94.4%), watery diarrhea (88.9%), and abdominal pain (66.7%). Salmonella enterica serovar Enteritidis was identified from rectal swab culture of all 5 cases. About 61.11% of the cases had clinical onset during 00.00–04.00 am on 21 February 2018. The epidemic curve showed a common-source outbreak pattern. The median incubation period was about 9 hours. All the cases were found in 15–59 year age group. Those living in the village where the calf was slaughtered had a significantly higher attack rate than those living in another village. A retrospective cohort study revealed that consumption of uncooked veal, organs or bile was significantly associated with illness. Salmonella organisms were also isolated from the uncooked veal and bile. The villagers who slaughtered this calf reported no experience of the cattle slaughtering.
Conclusions and discussions: An outbreak of food poisoning caused by S. enterica serovar Enteritidis occurred among the villagers who were exposed to foods made from veal and organs of the calf in Ponenakaew District, Sakhon Nakorn Province. Of 49 exposed villagers, 18 (36.7%) had food poisoning. The source of transmission might be uncooked bile or veal which was contaminated with the organisms during slaughtering.