Key Points

• In 2024, 148 cases of Legionnaires' disease were reported in the Nouvelle-Aquitaine region.

• The notification rate was 2.2 cases per 100,000 inhabitants, below the national rate (2.8 cases). It has decreased slightly compared to 2023 and 2022.

• Significant disparities exist between departments, with age-standardized rates ranging from 1.2 cases per 100,000 inhabitants in Deux-Sèvres to 3.8 cases in Charente. Gironde, the region’s most populous department, recorded the highest number of Legionnaires’ disease cases in 2024 (n=38).

• The characteristics of the cases (mostly men, median age of 65) were comparable to previous years, and the majority of cases were hospitalized.

• The case fatality rate was 8% (12 deaths), comparable to the national rate (9%).

• A Legionella strain was isolated in 38 cases (26%), leading to a comparison of clinical and environmental strains in only one case, which proved to be identical, thereby identifying the source of contamination.

• No risk exposure was reported through mandatory reporting for 62% of cases.

• The study on sporadic cases of Legionnaires’ disease and household exposure (LEGIODOM), led by the National Legionella Reference Center (CNR-L) in collaboration with Santé publique France, began on October 1, 2024, for a duration of two years; its objective is to document the proportion attributable to contamination of household water systems.