WEST NILE VIRUS DETECTED IN THREE CARRION CROWS IN BELGIUM

In July 2026, three juvenile carrion crows (Corvus corone) were brought to a local wildlife rehabilitation centre after developing neurological signs and general weakness. Despite supportive care, the birds died shortly afterwards.

Further analysis was warranted to determine the cause of death. The birds were submitted for post-mortem examination through the disease surveillance program of the Agency for Nature and Forests. Testing of pooled brain tissue from all three birds was positive for West Nile virus (WNV).

A virus on the move

West Nile virus is a mosquito-borne virus belonging to the genus Flavivirus. It can infect a wide range of animals. The virus is mainly transmitted by mosquitoes, which become infected when they feed on infected birds. Mosquitoes can then transmit the virus to other animals and, occasionally, to humans.

WNV has been spreading across Europe in recent years and has been detected in several European countries, including Belgium, the Netherlands, France and Germany. In August 2025, the virus was detected for the first time in wild birds in Belgium. The risk of infection is highest during the warmer months, when mosquitoes are most active. Avoiding mosquito bites is therefore an important way to reduce the risk of this zoonotic infection. A licensed vaccine to prevent WNV is currently unavailable.

Why crows are important

Carrion crows and other members of the crow family (Corvidae) are particularly susceptible to WNV. Infected crows can develop neurological signs and may die rapidly, sometimes without showing obvious abnormalities during post-mortem examination. This was also the case in the three crows described here. Apart from an empty stomach and a few minor findings, there were no striking lesions. Microscopic examination revealed only a mild inflammatory reaction in the central nervous system of one bird.

Continued surveillance is essential

The detection of WNV in these three crows is particularly relevant in light of another recent finding. Beginning of August, WNV was also detected in a horse showing neurological signs in the Brussels region. This was the first reported positive case in a horse in Belgium. Together, these findings highlight the importance of continued surveillance of West Nile virus in wildlife and domestic animals.

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Would you like to learn more about wildlife diseases? Check out this alphabetical list of wildlife diseases or explore other blog posts about diseases in wild animals on our website!