Austria is experiencing a notable increase in cases of West Nile virus (WNV), with 2024 marking a record year for confirmed infections. A long-term study by the Center for Virology at the Medical University of Vienna reveals a significant expansion of the virus’s reach, including the emergence of a new variant and a previously unaffected hotspot.
In 2024, a total of 37 confirmed cases of WNV were documented in Austria, surpassing the previous high of cases since the virus was first detected in the country in 2009. Nineteen of these patients required hospitalization due to severe symptoms. This surge in cases indicates that West Nile virus is now firmly established within Austria, according to researchers.
The northern region of Burgenland has been identified as a new regional hotspot for the virus. Notably, a variant of the virus previously prevalent in southern and southeastern Europe has been detected in this area, suggesting a geographical spread within Austria. “The fact that we are observing new regional hotspots underscores the need to remain vigilant even in areas that have been less affected so far,” says Judith Aberle, Professor of Virus Immunology at the Medical University of Vienna and head of the study.
West Nile virus is transmitted to humans through the bite of native Austrian mosquitoes, specifically those of the Culex genus. These mosquitoes are most active during dusk and nighttime hours. While approximately 80% of individuals infected with WNV do not exhibit any symptoms, around 20% may experience flu-like symptoms such as fever, headache, and body aches. Less commonly, less than 1% of those infected develop severe neurological complications, including meningitis or encephalitis.
Researchers emphasize that the actual number of WNV infections is likely significantly higher than reported, due to the large proportion of asymptomatic cases. This underscores the importance of heightened awareness among healthcare professionals, particularly during the summer months. Professor Aberle advises that patients presenting with meningitis or encephalitis, even without a history of travel, should be considered for possible WNV infection.
Currently, there is no commercially available vaccine to prevent West Nile virus infection. Preventative measures focus on minimizing mosquito exposure. These include using insect repellent, wearing protective clothing, and eliminating standing water where mosquitoes can breed.
The West Nile virus originated in Africa, with the first isolation occurring in the West Nile district of Uganda in 1937. The virus is primarily maintained in wild bird populations and transmitted to humans through the bites of infected mosquitoes. Since its emergence in Europe in the early 2000s, WNV has become endemic in many countries, with larger outbreaks observed in southern and southeastern Europe. Italy, for example, has recently reported fatalities linked to WNV infection.
The findings from the Medical University of Vienna’s study, in collaboration with the Austrian Agency for Health and Food Safety (AGES), analyzed data collected between 2009 and 2024. This comprehensive analysis provides a clear picture of the evolving WNV situation in Austria and reinforces the need for continued surveillance and public health preparedness. The Robert Koch Institute (RKI) in Germany also anticipates further establishment of WNV within the country.
Health officials continue to monitor the situation closely and recommend that individuals take appropriate precautions to protect themselves from mosquito bites, particularly during peak mosquito activity periods.
