A Community Waterborne Salmonella Bovismorbificans Outbreak in Greece

Abstract

Background: In August 2022, the Hellenic National Public Health Organisation was notified about a gastroenteritis outbreak in town A in Southern Greece. Investigations aimed to identify the source and implement control measures. Methods: Case definition categories were used in a 1:3 case–control study. Cases and controls were interviewed about various exposures. Cases’ stool samples were cultured on agar plates and characterised by serotyping, antimicrobial susceptibility testing and Pulse Field Gel Electrophoresis (PFGE). Environmental investigations included tap water sampling for microbiological and chemical analysis in town A and inspection of the water supply system. Results: We identified 33 cases (median age: 17 years). Tap water consumption was the only significant risk factor for gastroenteritis (OR = 5.46, 95% CI = 1.02–53.95). Salmonella (S.) Bovismorbificans isolated from eight stool and one tap water samples had identical PFGE profiles. No resistant isolates were identified. Residual chlorine levels were lower than the acceptable limits before and during the outbreak. We advised consumption of bottled water and adherence to strict hand hygiene rules until tap water was declared suitable for drinking. Conclusions: Epidemiological and molecular data revealed a waterborne S. Bovismorbificans outbreak in town A. We recommend local water safety authorities to ensure that residual chlorine levels comply with the legislation towards water safety planning, to mitigate risks.

Gastroenteritis Outbreaks after Contamination of Water Supply Systems: Public Health Response Gaps and Challenges, Greece, 2004–2023

“…Water sampling after the chlorination of the water supply system was reported in three (20%) outbreaks ( Table 1 ). The causative agent was isolated in both clinical and water samples in one (6.25%) of the sixteen WBOs, for which the respective samples were collected [ 19 ].…”

“…Finally, the lack of action plans, preparedness protocols, and training of the local authorities to conduct environmental investigations in the context of an outbreak, despite the fact that the World Health Organization has stressed their importance, highlight the response limitations [ 32 ]. This became evident in the case of a S. Bovismorbificans outbreak [ 19 ], where the pathogen was identified in both clinical and water samples. Although the coordination of the investigation was initiated promptly, the notification itself was delayed.…”