年度流行病学报告：军团病

Annual Epidemiological Report for 2024 Legionnaires' disease Key facts •In 2024, the annual notification ratefor Legionnaires’ diseaseincreased to 3.4cases per 100 000population, up from the3.2cases per 100 000 population reported in 2023.•Notification rates remained heterogenous across the EU/EEA, varying from less than 0.5 per 100 000population to the highestcruderate of9.6cases per 100 000 population reported by Slovenia. Fourcountries (France, Germany, Italy, and Spain) accounted for 71% of all notified cases.•Males aged 65 years and above werethemost affected (13.0cases per 100 000 population).•Eightcountries reported a total of 32community-or hospital-acquired outbreaks with a total of 365cases. Introduction Legionnaires’ disease is a multi-system diseasethatcauses pneumonia due to an infection withLegionellabacteria,most commonly of the speciesLegionellapneumophila. The bacteria are found in the natural environment, soil andwater, but they can become a health risk when they grow within engineered systems that can produce inhalablewater aerosols. Cooling towers, evaporative condensers, humidifiers, decorative fountains, hot tubsandshowersare examples of water systems with identifiedLegionellarisks. Conditions that are favourable forLegionellagrowthare water temperatures in the range of 25–42 °C, stagnant water with sediment build-up,and low biocide levels.Theaerosolizationof thebacteria-contaminated water may cause sporadic cases or outbreaks. Methods This report is based on data for 2024 retrieved fromEpiPulse Caseson 23 September 2025for the annual data(LEGI)andtheoutbreak reporting schemeas of18December2025.A summary of data collated through theTravel Associated Legionnaires’ disease surveillance scheme is not included in this year’s report. The methods used to produce this report are published online by ECDC [1] together with an overview of thenational surveillance systems [2]. A subset of the data used for this report is available through ECDC’s onlineSurveillance atlas of infectious diseases[3]. The surveillance dataand presented here in this reportwere collected throughtwodifferent schemes: •Annual retrospective data collection of Legionnaires’ disease (LD) cases reported in EUcountries,as well asinIceland, Liechtenstein and Norway;thetime periods in results presented are based on reported datesforstatistics. Suggested citation: European Centre for Disease Prevention and Control.Legionnaires’ disease. In: ECDC. Annual epidemiologicalreport for 2024. Stockholm: ECDC; 2026. •Annual retrospective data collection of outbreak events detected and reported in EUcountries,as well as inIceland, Liechtensteinand Norway.The following thresholds for reporting outbreaks are used:−≥ five cases, if these are not exposed inthesame building, nor evidence of exposure tothesameaerosol-producing installation/device, nor microbiological evidence of linked cases;−≥ three cases, if these are exposed in the same building, or if evidence for exposure tothesameaerosol-producing installation/device, or if microbiological evidence of linked cases; Legionnaires’ disease cases should be reported to these surveillance schemes in accordance with the 2018 EU/EEAcase definition for confirmed cases or probable cases, that includes at least one positive laboratory test and aclinical diagnosis of pneumonia. Epidemiology In2024, 29countries reported 15362cases (Table 1), of which 14126(92%) were classified as confirmed.Thenumber of notifications per 100 000 population increased to 3.4,which continued an increasing trendobservedsince 2020.Four countries-France, Germany, Italy and Spain-continuedto account for most notifiedcases (71%), although their combined populations only representapproximately 50% of the EU/EEA population. Of 12041cases with known outcome,1117(9%) were reported tobefatal. Age-adjustednotification rates ranged from less than 1.0 cases per 100 000 population infivecountries (Bulgaria,Finland, Greece, Ireland, Romania) to 3.0 cases per 100 000 population or more intencountries (Austria,Belgium,Czechia,Denmark, Italy, Liechtenstein,Malta,Portugal,Slovenia, and Spain); see Table 1 and Figure 1. The distribution of cases per month (Figure 2) showsa seasonality trend,with most cases reported during thesummer in the EU/EEA.In 2024, mostcases(8 689, 57%) occurred between June and October,as inpreviousyears,however the number ofmonthly cases in the European spring and autumnwereconsistently above therange observed in the previousfouryears (Figure 3). Themonthly number of cases in September and Octoberwere below thehighest monthly number of casesever observed in the previous four years(2 308 cases seen inAugust2023representing 16% oftheannual totalthat yearand occurringintheabsence of any specific countryoutbreak event). Source: Country reports from Austria, Belgium, Bulgaria, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece,Hungary, Ireland, Italy, Latvia, Luxembourg, Malta, the Nethe