West Nile Virus Spreads in Belgium: Red Cross Tests Blood Donors in Vilvoorde
Belgian health authorities have confirmed West Nile virus infections in animals across two regions of the country, prompting alerts to hospitals and doctors and triggering precautionary blood donor testing. The Red Cross Flanders is now screening blood donors in the Vilvoorde area after a horse tested positive, while medical professionals in the Mechelen-Willebroek region have been placed on alert following detections in birds and another horse.
Regional Alerts Issued
Recent tests on birds and a horse confirmed the virus is circulating in the Mechelen-Willebroek region of Antwerp province, according to the city of Mechelen’s official announcement. The Flemish Department of Care has since alerted doctors and hospitals in the region so they can consider West Nile virus as a possible diagnosis when patients present with symptoms that cannot be attributed to another disease.
“So that doctors know that when they receive a patient whose symptoms they cannot immediately attribute to another disease, they also consider a possible West Nile virus infection,” Joris Moonens of the Flemish Department of Care told VRT NWS.
Moonens stressed there is no reason for major concern. “There is therefore no reason for major concern. But it is something we are following up on. We know the virus circulates in animals and we continue to monitor that and keep our healthcare providers informed,” he said.
Blood Donor Screening Underway
In a related development, Red Cross Flanders is testing blood donors in the Vilvoorde region of Flemish Brabant on instruction from the Federal Agency for Medicines and Health Products (FAGG), after a horse in that area tested positive for the virus in early August. Donors from Vilvoorde, Zemst, Steenokkerzeel, Machelen, and Grimbergen are being screened, as VRT NWS reported.
Belgium is unique in Europe in this approach. “All other countries only test when an infection in a human has been confirmed,” said Jan Poté of Red Cross Flanders. The organization has already conducted nearly 11,000 tests for West Nile virus and has found no infections to date.
Poté expects a similar instruction from FAGG for the Mechelen-Willebroek region. “I suspect that today or tomorrow we will also receive the instruction to start testing in that region as well,” he said.
First Horse Infection Confirmed
The first confirmed West Nile virus infection in a horse in Belgium was officially confirmed on August 7 by the Federal Agency for the Safety of the Food Chain (FAVV). The horse, located in the Brussels periphery, showed severe neurological symptoms and was euthanized. “West Nile virus has been detected in neighboring countries and many other regions in Europe in recent years. It is therefore no surprise that this virus is now also being detected in our country,” the FAVV stated in a VRT NWS report.
The case was initially reported on August 6 by the Walloon veterinary association UPV. “This case was not discovered through a surveillance system, but by a veterinarian who saw the sick horse and made the correct diagnosis,” said Pierre Paindaveine, president of the horse section of UPV, as reported by VRT NWS.
Virus Circulating in Birds Since 2025
West Nile virus has been progressively establishing itself in Belgium. In 2025, three crows tested positive for the virus. The virus was also detected in birds in May and July 2026. Wildlife Health Ghent confirmed that in July 2026, three young carrion crows with neurological symptoms and general weakness died shortly after being brought to a local wildlife rehabilitation center; pooled brain tissue tested positive for West Nile virus.
A European-Wide Concern
The virus is currently circulating in humans across multiple European countries, including Italy, Greece, Spain, France, Germany, Romania, and North Macedonia. The European Centre for Disease Prevention and Control (ECDC) reported that 12 European countries have recorded West Nile virus cases this year, with most cases registered in Italy (311) and Greece (157), according to VRT NWS reporting.
North Macedonia is experiencing a particularly severe epidemic, with at least 5 deaths and 43 confirmed cases. Health authorities there have launched large-scale aerial spraying operations against mosquitoes.
Understanding the Virus
West Nile virus is a mosquito-borne flavivirus that circulates naturally between mosquitoes and birds. Mosquitoes become carriers when they bite an infected bird and can then transmit the virus to other species, including horses and humans. Humans and horses are considered “dead-end hosts” and cannot transmit the virus further.
Approximately 80 percent of infected people show no symptoms. About 1 in 4 develop flu-like symptoms after an incubation period of 2 to 14 days. About 1 percent develop severe neurological conditions such as encephalitis or meningitis, with the risk higher among elderly people and those with weakened immune systems. There is no vaccine for humans and no specific treatment, as detailed in VRT NWS’s background analysis.
Climate Change Connection
Researchers at VUB and ULB demonstrated in a 2024 study that climate change plays a major role in the spread of West Nile virus in Europe. The virus’s spread is linked to high temperatures in spring and summer, dry periods in summer, and warm winters.
“This is the face of climate change. Alongside escalating climate extremes, the emergence of tropical diseases in Europe is unfortunately one of the many logical consequences of our addiction to oil, coal, and gas,” said Wim Thiery, climate scientist at VUB.
What to Watch For
Authorities advise residents in affected regions to take precautions against mosquito bites, including wearing long clothing, using insect repellent, and installing screens on windows and doors. The Flemish Department of Care provides guidance on prevention measures.
While the risk to human health remains limited, the continued spread of the virus in animals across Belgium suggests that vigilance will be needed throughout the mosquito season, which typically peaks between July and September. Health authorities will continue monitoring the situation and testing blood donors as a precautionary measure.