Key Points

In 2024, the number of Legionnaires' disease cases reported to Santé publique France was lower than in 2023, but comparable to that of 2022.

• 1,939 reported cases, representing a reporting rate of 2.8 cases per 100,000 inhabitants

• A 12% decrease compared to 2023

• Case characteristics comparable to those observed in recent years

• Regions with the highest reporting rates: Provence-Alpes-Côte d’Azur (3.9 cases per 100,000 inhabitants) and Auvergne-Rhône-Alpes (3.7 cases per 100,000 inhabitants)

• Case fatality rate of 9% (160 deaths)

• 91% of cases diagnosed initially by urinary antigen test and 5% by PCR

• 515 clinical strains available, representing 27% of cases, a proportion stable compared to 2023

• For 74% of the 76 cases where a comparison between the clinical strain and environmental strains was possible, genomic concordance of the strains helped identify the source of contamination

• A cluster of 17 cases, with a cooling tower identified as the most likely source of contamination

• 63% of cases had no reported risk exposure in mandatory reporting

In October 2024, launch of the LEGIO-DOM exploratory study aimed at documenting the proportion of Legionnaires’ disease cases that can be linked to household contamination via water distribution systems, with the participation of Regional Health Agencies (ARS) from all regions of mainland France except Occitanie.

Learn more about Legionnaires' disease