West Nile virus (WNV) is increasingly prevalent in Europe, with 14 countries reporting 1,112 autochthonous (locally acquired) human cases through December 3, 2025, according to a response to a parliamentary question. The virus resulted in 97 deaths across the continent during that period.
The spread of WNV is a growing public health concern, as the virus can cause neurological illness and, in some cases, death. In 2025, authorities also reported 186 outbreaks of WNV in equids (horses and related animals) and 359 outbreaks in birds across Europe.
As of now, Belgium has not reported any human or mammal cases of WNV. However, the first cases observed in the country, detected in August 2025, involved wild birds. These cases were identified through a study initiated in 2024 by the Service de Santé et Pathologie de la faune sauvage (Wildlife Health and Pathology Service) at the University of Liège (ULiège), in collaboration with Sciensano. The study utilizes non-invasive sampling methods on live birds admitted to wildlife rehabilitation centers.
“The study will be continued in 2026 and 2027,” explained Annick Linden, Professor of Wildlife Health and Pathology at the Faculty of Veterinary Medicine at the University of Liège. In addition to this ongoing research, an interfaculty team at ULiège, comprising doctors, veterinarians, and bioengineers, has compiled thousands of plasma samples from wild animals, horses, and humans. They are currently conducting a serological investigation to determine the prevalence of infections caused by Flaviviruses – including WNV – in Wallonia. The dengue and Zika viruses also belong to the Flavivirus family.
Walloon Minister of Agriculture Anne-Catherine Dalcq stated in late December that the detection of infected birds in August “marked a significant step in the local emergence of West Nile virus and indicated a probable recent introduction of the virus into the national ecosystem.” She added, “These findings underscore the demand to strengthen surveillance and increase preparedness in public health.”
