Implementation of a nationwide Waterborne disease outbreak surveillance system in France

Abstract

Abstract Issue/Problem Waterborne disease outbreaks (WBDOs) remain a public health issue in developed countries, but to date the surveillance of WBDOs in France, mainly based on the voluntary reporting of clusters of acute gastrointestinal infections (AGIs) by general practitioners to health authorities, is characterized by low sensitivity. In this context an integrated and automatized approach to detect WBDO relying on the identification of clusters of medicalized AGI cases sharing a same drinking water networks (DWN) was developed, evaluated in a simulation study and tested in a pilot study by the French National Public Health Agency. Description of the problem Two national big databases support the detection process of potential WBDO: health insurance database for AGI, ministry of health database for drinking water system information. Each detected outbreak has to be investigated regarding environmental criteria during the days before the onset of the outbreak: results on bacterial water monitoring, weather (e.g. heavy rain), technical incidents in the drinking water system (e.g. chlorination breakdown, alarm malfunction). To evaluate the strength of association with drinking water, four levels are proposed based on epidemiological and environmental criteria (strong, probable, possible and undetermined). Results The WBDO surveillance system has been implemented in all french departments since start of 2019 and support by the ministry of health. A web-application, named “EpiGEH”, was also developed to support the surveillance system. A retrospective study between 2010 and 2017 has detected almost 300 to 550 potential WBDO per year while voluntary reporting identified 2 to 3 WBDO each year during the same period. Lessons Such a specific surveillance system should help health authorities to formulate recommendations regarding the management of drinking water systems and propose appropriate preventive measures, in accordance with the water safety plans. Key messages The WBDO surveillance system based from health insurance databases constitutes a daily surveillance system of drinking water quality. The WBDO surveillance system should drastically improve the detection sensitivity by a factor 100 to 200 compared to voluntary reporting.