Key Points

This Public Health Bulletin presents a regional overview of the surveillance of waterborne acute gastroenteritis outbreaks from January 2010 to December 2021. These analyses are produced at the national level and across all regions based on indicators derived from health insurance data and information collected regionally through health and environmental investigations conducted by the Regional Health Agencies (ARS).

• Surveillance of waterborne acute gastroenteritis outbreaks:

  • A unique nationwide multi-source surveillance system led by Santé publique France in collaboration with the Directorate General for Health and the Regional Health Agencies;

  • Providing epidemiological indicators (signals of clusters of acute gastroenteritis cases) related to the infectious risk associated with tap water consumption, improving understanding of the health impact of these events, and targeting measures to secure and control water distribution systems against infectious risks;

  • Enabling the identification of water distribution units involved in clusters of acute gastroenteritis and the circumstances under which contamination entered the network;

  • Operational nationwide since March 2019, with retrospective data analysis dating back to 2010.

• Study periods for the development of this BSP:

  • From January 2010 to December 2021 for all detected signals;

  • Particular focus on the period from 2019 to 2021, corresponding to the prospective implementation period of the system

• Key data for Occitanie (January 2010 to December 2021, data as of 02/07/2023):

  • 1,059 reports detected during the 2010–2021 period corresponding to clusters of cases of acute gastroenteritis with a plausible waterborne origin;

  • 188 reports considered a priority for environmental investigations due to drinking water distribution systems repeatedly implicated in multiple health reports (120 water distribution systems);

  • 34 reports fully investigated by the ARS in 5 departments;

  • 85% of the reports investigated by the ARS had a waterborne origin, which was confirmed by the environmental investigation;

  • 29 waterborne outbreaks (including 7 since 2019) identified by the system (of which only 2 had been reported to the ARS during the same period);

  • A vulnerability in the water source supplying the affected water distribution systems was identified in 30% of the outbreaks, and an operational malfunction (treatment, distribution) in 17% of cases.