The number of horses with a recent West Nile virus infection in the Netherlands has risen to 58 (as of 11 September). The virus has also been detected in wild birds and mosquitoes. These findings show that West Nile virus is circulating in several parts of the Netherlands.
Infected horses have so far been identified in the provinces of South Holland, North Holland, North Brabant, Utrecht and Gelderland. This means that infections have now been detected across several areas in the west and center of the Netherlands.
The number of cases may increase further in the coming weeks. As mosquito activity declines due to lower temperatures later in the year, the likelihood of further transmission of the virus will also decrease.
Wild birds and mosquitoes
West Nile virus is also being detected more frequently in wild birds. The national West Nile virus working group reports that 39 wild birds have now tested positive (as of 11 September). The relatively high mortality among corvids is particularly notable. Mortality among wild birds can indicate that the virus is actively circulating in an area. Infected mosquitoes have also been detected, confirming that the virus is circulating at multiple locations in the Netherlands.
Neurological signs in horses
Equine veterinarians are advised to remain alert to neurological signs that may be associated with West Nile virus infection, particularly in areas where infections have been detected.
The number of blood samples submitted for testing has increased sharply in recent weeks. As a result, the available budget for free-of-charge exclusion diagnostics has been fully used. This form of monitoring has therefore been discontinued. Routine diagnostics for West Nile virus remain available.
Timely diagnosis and reporting remain important. They support accurate diagnosis and appropriate advice for horse owners and help monitor the spread and development of West Nile virus in the Netherlands.
