A six-year-old horse in the Netherlands has tested positive for antibodies against West Nile virus (WNV). Although the analysis was done on a non-official sample, the European Reference Laboratory for WNV in horses has since confirmed the infection using a virus neutralisation test.
Infected mosquitoes found nearby
This marks the first confirmed WNV infection in a horse in the Netherlands. The horse was imported from Ireland in June 2024 and had not been vaccinated against WNV. Since November 2024, it was kept at the location, which means the infection was acquired locally. At about 25 km from infected horse, the virus was recently detected in mosquitoes.
Neurological signs in the horse
The horse in question was being treated by a local veterinary practice. Due to neurological signs (muscle tremors, reduced awareness and weakness in the limbs), the veterinarian collected a blood sample on 18 September for testing at the Dutch animal health services Royal GD.
Vets on the front lines
‘Vets are often on the front lines when it comes to emerging diseases,’ commented Volker Moser, President of the UEVP. ‘This is of particular importance for public health as many of these diseases, like West Nile disease, also affect humans.’ Veterinary practitioners play a crucial role in One Health, he added.
Horses, a reliable WNV sentinel for humans
WNV is spread by migratory birds via mosquitoes. Horses and humans are end hosts, meaning they cannot transmit the virus further. Horses are considered a reliable sentinel for the risk to humans. Although most equine infections are mild or asymptomatic, some horses develop severe neurological signs. Annual vaccination remains the most effective protection.
WNV spreading to the north and west
WNV is by no means new in Europe, and the virus is being closely monitored, both in human and equine medicine. However, where the disease was largely confined to the Mediterranean basin, it has spread over the past years towards central Europe and Germany – and now the Netherlands.
(photo ©Petra/Pixabay)