Acute gastroenteritis outbreak linked to Escherichia coli contamination in a swimming pool during a state-level school sports championship

Acute gastroenteritis (AGE) outbreaks caused by Escherichia coli are typically foodborne, and linked to contaminated food or water sources. This article describes an outbreak associated with a public aquatic facility during a state-level championship in Johor Bahru, Malaysia, in July 2024. The outbreak was linked to a malfunctioning pool filtration system and inadequate maintenance, creating an unusual environmental source of E. coli transmission. Epidemiological investigations were conducted, along with environmental assessments and laboratory analyses of clinical (rectal swabs and stool cultures) and environmental (water and surface swabs) samples. A total of 92 AGE cases were identified among 917 exposed individuals, yielding an attack rate of 10.03%. Symptoms included diarrhea, abdominal pain, nausea, vomiting, and fever. Laboratory investigations revealed E. coli contamination in five water samples, with levels exceeding permissible limits. Low residual chlorine levels (<0.2 mg/l) were observed. Leptospira species were detected in two water samples, but no confirmed leptospirosis cases were reported. Environmental assessment revealed poor pool hygiene, malfunctioning filtration systems, and incomplete renovations. This outbreak underscores the critical need for stringent hygiene standards in public swimming pools and consistent maintenance of water quality to prevent waterborne disease outbreaks in aquatic facilities.