Research – Implementation of a national waterborne disease outbreak surveillance system: overview and preliminary results, France, 2010 to 2019

Eurosurveillance

Waterborne disease outbreaks (WBDO) are still a public health issue worldwide [13]. They are generally caused by the microbiological contamination of tap water, and acute gastroenteritis (AGE) is the most common syndrome in affected people. Faced with this issue, many countries have implemented dedicated surveillance systems [1,35]. However, notification processes (voluntary or mandatory) vary, as do definitions for WBDO. Standardised information is collected including epidemiological, clinical and, occasionally, biological data, as well as data on the drinking water supply zone (WSZ) in question and operating and distribution incidents. A WSZ refers to a geographically defined area within which water intended for human consumption comes from one or more sources, and where water quality may be considered as approximately uniform. Although most surveillance systems are affected by under  detection, assessments all tend to highlight the same risk factors: rainy events leading to pollution and flooding of the water resource, microbiological vulnerability of the resource, operating incidents (disinfection failure, filtration incident) or a distribution incident (pipeline break, backflow of waste water to the drinking water supply) [6]. Moreover, contributing environmental factors may be aggravated by climate change, thereby increasing the health burden attributable to tap water [7,8].

In France, health authorities notify WBDO to Santé publique France (SpFrance, the French Public Health Agency). SpFrance then investigates the reported issue [912]. There is no standard declaration procedure for reporting WBDO. They are usually notified to health authorities through voluntary reporting by general practitioners or pharmacists following official drinking water monitoring results, or following consumer complaints (smell, taste, etc). Rarely, WBDO are also notified through the Food-borne Infectious Outbreak (FIO) mandatory surveillance system, which is also managed by SpFrance. The lack of a specific WBDO surveillance system leads to underestimation of their health impact. Studies based on improving sensitivity, by using health insurance data to record medicalised acute gastroenteritis (mAGE) cases, have proven both their utility in the study of infectious risk attributable to tap water, and their applicability in retrospective WBDO detection systems [1316].

In this context, SpFrance, in partnership with the Ministry of Health and regional health agencies (ARS), designed a national French WBDO surveillance system based on health insurance data. The 3-year start-up period to test the system commenced in April 2019. Its main objectives are (i) to facilitate the identification and management of WSZ that need to be secured and made safe to protect consumers’ health and (ii) to improve contamination prevention through increased knowledge of WBDO in France and associated risk factors. Furthermore, this new system will provide epidemiological indicators to better estimate the health impact of WBDO.

This article presents the structure and organisation of this new French WBDO surveillance system. We focus on the web-based application EpiGEH, which was specially developed for the system by SpFrance.

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