Food Poisoning Outbreak Investigation in Sub-district Bansan, Srisamrong District, Sukhothai Province, June 14 - July 14, 2012

Abstract

On 26^th June 2012, the SRRT in Sawankhalok District was notified that 10 students from the antiamphetamine camp at a temple had symptoms of food poisoning. An outbreak investigation was conducted from 26 June to 14 July 2012 in order to describe epidemiological characteristics, identify source of infection and implement outbreak control measures. Active case finding was conducted by data collection and interview. A case was defined as a person from School A or Bansan Sub-district who had 2 or more of the following signs and symptoms: vomiting, abdominal pain, diarrhea or fever. Suspected food specimens were collected and environmental surveys were carried out in both School A and Bansan Sub-district. A retrospective cohort study was conducted for students in School A.
Of total 102 cases identified, 16 cases were from Bansan Sub-district (15.79%) and 86 cases were from School A (84.21%). None of the teachers, cleaners and cooks was sick. Majority of the cases developed vomiting (91.17%), followed by abdominal pain, headache, diarrhea and fever. The outbreak was likely to be caused by a common source, with the highest attack rate in grade 5 (attack rate = 0.46). Drinking of water from drinking water cooler was likely to be a risk factor for this outbreak. Specimens collected were foods and tap water from the school, and water from the water supply tank 1 in Bansan Sub-district. Total 60 rectal swab specimens were collected and sent to laboratory for testing. Shigella group B was tested positive from rectal swab specimen of a sick student who joined the camp while Shigella group C was detected from rectal swab specimen of a sick student who did not join the camp. There was no residual chlorine in water from tap water in the school and the water supply tank 1. In conclusion, since no etiological agent was identified for this food poisoning outbreak, it was likely to be caused by drinking of low quality water.