Legionnaires’ disease - Annual Epidemiological Report for 2024
Surveillance and monitoring
Legionnaires’ disease is a multi-system disease that causes pneumonia due to an infection with Legionella bacteria, most commonly of the species Legionella pneumophila. The bacteria are found in the natural environment, soil and water, but they can become a health risk when they grow within engineered systems that can produce inhalable water aerosols. Cooling towers, evaporative condensers, humidifiers, decorative fountains, hot tubs and showers are examples of water systems with identified Legionella risks. Conditions that are favourable for Legionella growth are water temperatures in the range of 25–42 °C, stagnant water with sediment build-up, and low biocide levels. The aerosolisation of the bacteria-contaminated water may cause sporadic cases or outbreaks.
Key factys
In 2024, the annual notification rate for Legionnaires’ disease increased to 3.4 cases per 100 000 population, up from the 3.2 cases per 100 000 population reported in 2023. Notification rates remained heterogenous across the EU/EEA, varying from less than 0.5 per 100 000 population to the highest crude rate of 9.6 cases per 100 000 population reported by Slovenia. Four countries (France, Germany, Italy, and Spain) accounted for 71% of all notified cases. Males aged 65 years and above were the most affected (13.0 cases per 100 000 population). Seven countries reported a total of 31 community- or hospital-acquired outbreaks with a total of 355 cases.
Publication file
Legionnaires’ disease - Annual Epidemiological Report for 2023
English (717.25 KB - PDF)
