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

Abstract

waterborne disease outbreaks (WGDOs) following the contamination of drinking water remain a public health concern. The current study aims to assess the occurrence and identify gaps in the notification and investigation of WGDOs in Greece. Data for 2004-2023 were retrieved and summarized. Thirty-five outbreaks with 6128 recorded cases were identified. The median time from the date of onset in the first cases to reporting was 7 days (range: 1-26 days). Authorities were informed by health care services in thirty (85.7%) outbreaks and by the media in five (14.3%). The investigation methods used varied. An analytical study was conducted in nine (25.7%) outbreaks and the testing of clinical samples in twenty-seven (77.1%). In three (11.1%) outbreaks, clinical samples were simultaneously tested for multiple bacteria, viruses, and parasites. Water samples were collected in nineteen (54.3%) outbreaks (in three after chlorination) with a mean time lag of 5 days (range: 1-20 days) from the first cases. A pathogen in clinical samples was identified in 20 (57.1%) outbreaks and, in 1 (6.25%), the same microorganism was isolated in both clinical and water samples. delays in reporting and the heterogeneity of investigations depict that the surveillance of WGDOs and response practices should be strengthened, and operational procedures should be standardised.