Epidemiological study of food poisoning outbreaks in prisons during 2015-2024 to develop disease surveillance, prevention and control measures

Abstract

Introduction: Food poisoning is a major public health concern in prisons due to overcrowding and mass catering. Despite the implementation of the "Ratchathan Pan Suk" project in 2019 to improve inmates' health, outbreaks continue to occur. This study aimed to describe the epidemiological characteristics, identify risk factors, and evaluate the effectiveness of surveillance, investigation, and control measures for food poisoning outbreaks in Thai prisons from 2015 to 2024.

Methods: A Retrospective Descriptive and Situation Analysis Study was conducted using secondary data from the Event-Based Surveillance (EBS) system, Department of Disease Control. Descriptive statistics were used to illustrate outbreak characteristics. The Mann-Whitney U test was applied to compare the duration of disease surveillance and control between the pre-project period (2015–2019) and the project implementation period (2020–2024), with a statistical significance level of 0.05.

Results: Total of 46 outbreaks were identified, accounting for 8,389 cases and 1 death (case fatality rate 0.01%). Attack rates varied widely from 0.56% to 55.43%. The leading causative agents were Salmonella spp. (15 events), followed by Bacillus cereus, Aeromonas spp., and Norovirus (9 events each), along with histamine toxicity (2 events). Analytical results showed the increasing number of reported events from 18 events (4,000 cases) to 28 events (4,389 cases and one death). The duration of disease control significantly decreased during the project implementation period to a median of 4.00 days, compared to 8.50 days in the pre-project period (p = 0.024). The outbreak duration also showed a decreasing trend from 4.50 to 2.00 days (p = 0.051). The response time remained consistently rapid across both periods (median 0 days). The main risk factors stem from deficiencies in food and water sanitation, including mass food preparation in advance and not storing it at the proper temperature, leading to the growth of toxins; undercooking food; not reheating food before consumption; improper cold chain management; and malfunctioning chlorination systems.

Discussion and Recommendations: The Ratchathan Pan Suk project tangibly facilitated public health integration, expediting outbreak containment by accelerating the disease reporting system and rapid control measures. Recommendations for disease control measures include: regularly maintaining the chlorine dosing system for drinking and general water use; strictly controlling the storage temperature of raw materials, meat, and seafood (especially marine fish to prevent histamine formation); reheating cooked food left at room temperature for more than two hours before consumption; preventing inmates from hoarding food; and strictly controlling the personal hygiene of food handlers.