Eurosurveillance - Volume 31, Issue 1, 08 January 2026

Carbapenemase-producing Enterobacterales (CPE) cause infections, particularly nosocomially, with limited treatment options. NDM-1-producing Klebsiella pneumoniae cases have substantially increased since 2022, associated with the Ukraine war.

We aimed to investigate transmission patterns using Germany’s Integrated Genomic Surveillance (IGS), combining notifications and sequence data.

We selected NDM-1-producing K. pneumoniae cases, confirmed by isolates between 1 January 2022 and 28 February 2023. Isolates were Illumina whole genome-sequenced and linked to notifications. Clusters were defined as ≤ 12 allelic differences in core genome-wide single nucleotide variant-based genotyping. Cluster categories were: ‘no exposure abroad’, ‘exposure in Ukraine’ or ‘other exposure abroad’ if ≥ one case stayed in Ukraine or elsewhere. Follow-up of 13 clusters examined further exposure information.

Among 424 cases of most frequent sequence types, 326 (77%) belonged to 61 clusters. Seventeen (28%) clusters were associated with no exposure abroad, 33 (54%) with exposure in Ukraine, seven (11%) with other exposure abroad, and four (7%) had insufficient data. Cases in clusters with exposure in Ukraine were more dispersed, younger, and more often wound-infected than in other exposure location categories (p < 0.01). Cluster follow-up revealed one cluster with all cases from Ukraine or Russia, another with nosocomial transmission following case importation, and a third with all cases from one German hospital without exposure abroad.

Most cases were in clusters, suggesting preventable chains of transmission. Three patterns emerged: transmission abroad, transmission in German hospitals from imported cases or local outbreaks. IGS can identify where transmission could be interrupted. International cooperation needs strengthening to prevent CPE spread.

West Nile virus (WNV) and Usutu virus (USUV) outbreaks in Europe pose growing public health concerns. In Austria, human WNV and USUV infections occur nearly every year since 2009 with notable case number variations.

We analysed annual incidences and spatiotemporal distributions of human WNV and USUV infections in Austria in 2009–2024.

Annual incidence rates of laboratory-confirmed WNV and USUV cases recorded through the national surveillance were calculated, stratified by age, sex, clinical presentation, exposure place and virus sequence.

During 2009–2024, recorded case numbers were highest in 2024, with 37 WNV (19 male/18 female; median age: 62 years, range: 18–88) and 27 USUV infections (18 male/9 female; median age: 59 years, range: 20–69). Nineteen WNV cases developed West Nile neuroinvasive disease, while no USUV cases had neurological disease. Thirty-four of the WNV cases and all USUV cases were locally acquired. In northern Burgenland, an eastern Austrian region with an avian hotspot and only sporadic cases previously reported, WNV and USUV incidences respectively rose from averages of 0.6 and 1.0 per 100,000 in previous years to 6.6 and 4.2 per 100,000 in 2024. All 25 sequences analysed in 2024 from locally acquired WNV cases were of lineage 2. Among 15 USUV sequences, 14 belonged to the Europe-2 and one to the Africa-3 clade.

Human WNV and USUV infection increases in a previously low-incidence region underscore their increasing public health impact in Austria. Strengthening surveillance and response measures is essential for early detection, guiding prevention efforts, and ensuring blood donor safety.