Key Points

• In 2025, 76 cases of Legionnaires' disease were reported in Normandy.
• The regional notification rate was 2.2 cases per 100,000 residents, a slight decrease from 2024 but higher than in 2023. This rate remained lower than the national rate (2.8 per 100,000 inhabitants), as in previous years.
• The Eure department had the highest reporting rate in the region (3.4 per 100,000 inhabitants), as it did in 2023 and 2024.
• The characteristics of the cases were comparable to those of previous years. The cases primarily involved men, and the median age was 62 years. The case fatality rate was 2.7% (2 deaths), lower than that observed during the 2015–2024 period (8.0%).
• Antigen detection remained the primary diagnostic method, but the use of PCR continued to increase, rising from 26% in 2024 to 38% in 2025.
• A clinical strain of Legionella was isolated in 20 cases (26%, a proportion stable compared to previous years). Four comparisons with environmental strains were conducted: three revealed identical strains, found in vacation rentals or hotels.
• Risk exposure was reported in 29% of cases, primarily associated with travel. Environmental investigations conducted by the ARS Normandy in 2025 revealed Legionella contamination in domestic hot water systems at locations frequented by 12 cases.
• No clusters of cases were identified in Normandy in 2025.