An outbreak investigation of acute diarrhea from Shigella sonnei in a prison, Sikhio District, Nakhon Ratchasima Province, Thailand, 24th–30th March 2021

Abstract

Background: On March 24th, 2021, 8:30 AM, SRRT of Pakchong Hospital, Nakhon Ratchasima was notified about a cluster of 24 prisoners suffering from acute diarrhea. An outbreak investigation was performed from 24th–30th March 2021 to confirm the diagnosis, confirm the outbreak, describe the epidemiology of the outbreak and implement disease control measures.
Methods: A descriptive study was done by reviewing medical records, interviewing the patients and conducting active case finding. Retrospective cohort study was conducted to identify the meals and sources of drinking water causing the acute diarrhea in the highest attack rate inmate–wing (Wing–5). The environmental study was conducted by surveying the Kitchen Wing, an inmate’s canteen and Wing–5. We interviewed prison officers and inmates in the topic of food preparing, inmate’s eating behaviors and drinking water management system. Laboratory study was performed by collecting rectal swab samples from the patients and cooks, swab samples from the cook’s hands, food containers, cooking utensils, and drinking water samples. Bacterial culture, virological examination and coliform bacteria were tested.
Results: Eighty-three diarrhea patients were identified from the preliminary investigation, with the top five clinical symptoms being abdominal pain, fatigue, headache, watery diarrhea, and loose stool. The highest attack rate was in Wing 5. Therefore, our team conducted a survey in Wing 5, and found 206 (13.67% attack rate) of 1,507 inmates met the case definition. The foods that related to risk of acute diarrhea were foods purchased from the inmate’s canteen. Unhygienic cleaning of food trays, food storage behavior and broken UV lamp in the water purifier of Kitchen Wing increased risk of diarrhea. Laboratory tests detected Shigella sonnei (Group B) in 2 of 17 rectal swab culture samples, Bacillus cereus was detected from the hand swab of a Kitchen Wing cook, Aeromonas and Bacillus cereus were cultured in 5 drinking/cooking water samples. Coliform bacteria were found in a knife from an inmate’s canteen and a food tray from Wing 5 by SI–2 coliform test.
Conclusions and discussions: An outbreak of acute diarrhea occurred in the prison, Sikhio District, Nakhon Ratchasima Province. The outbreak was caused by Shigella sonnei (Group B). The risk factors were buying food from the inmate’s canteen including risky food storage behavior, unhygienic cleaning of food trays and contaminated drinking water sources. Health education, environmental improvement and teaching proper cleaning of the food containers were done to control the disease and inform the prison officers about improving standard water filtration systems.