Vienna – Public health officials are closely monitoring a notable increase in West Nile virus cases in Austria, with a record 37 confirmed infections reported in 2024 – the highest number since the virus’s initial detection in the country in 2009. A new study from the Medical University of Vienna indicates the virus is now firmly established within Austria, and a previously unseen variant has been identified in the northern burgenland region [[1]].While the overall risk to the public remains low,experts emphasize the importance of vigilance and early detection due to the lack of a current vaccine.
VIENNA – A long-term study from the Center for Virology at the Medical University of Vienna has revealed a significant increase in West Nile virus infections in Austria. The country recorded 37 confirmed cases in 2024, the highest number since the virus was first detected there in 2009. This surge in cases is prompting health officials to monitor the spread of the mosquito-borne illness more closely.
The virus, transmitted by local mosquito species, caused illness in 37 people last year, with 19 requiring hospitalization for severe complications. The findings indicate West Nile virus is now firmly established in Austria, according to researchers.
“The substantial increase in cases demonstrates that West Nile virus is now firmly established in Austria,” said Judith Aberle, a professor of virus immunology at the Medical University of Vienna and lead researcher of the study at the Center for Virology.
Regional Shifts and New Viral Strain
The majority of infections in 2024 were concentrated in the northern Burgenland region. Notably, a virus variant previously seen primarily in Southern and Southeastern Europe was identified there for the first time, suggesting a geographic expansion of the virus within Austria.
“Observing new regional hotspots underscores the need for vigilance even in areas previously considered less affected,” Aberle explained. “During the summer months, clinicians should consider West Nile virus infection in patients presenting with meningitis or encephalitis, even without a history of travel.”
Researchers believe the actual number of infections is likely much higher, as only about one in five individuals infected with the virus develop symptoms, and severe neurological illness occurs in a small subset of cases. Currently, there is no effective vaccine available. Continuous monitoring is therefore crucial for early detection of new risk areas and appropriate responses to the virus’s spread.
The long-term study was conducted at the Center for Virology of the Medical University of Vienna in collaboration with the Austrian Agency for Health and Food Safety (AGES) and analyzed data from 2009 to 2024. The project, InFlaMe, is supported by the European Union under grant number 101191725.
Publication: Eurosurveillance
Increased incidence of human West Nile and Usutu infections in Austria, 2024: analysis of data from 2009 to 2024
David M Florian, Jeremy V Camp, Christof Jungbauer, Dirk Werber, Andreas Reich, Karin Stiasny, Stephan W Aberle, Judith H Aberle
https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2026.31.1.2500260
The rise in West Nile virus cases in Austria highlights the growing threat of vector-borne diseases in Europe, as climate change expands the range of mosquito populations.
