Westnile virus first found in the Netherlands

In the region of Utrecht, a whitethroat infected with the West Nile virus has been found. It is the first time that this virus has been found in the Netherlands, the National Institute for Public Health and the Environment (RIVM) announced.

The virus is transmitted by mosquitoes. They become infected by feeding on infected birds. These mosquitoes then spread the virus to other birds and sometimes to humans and other mammals, such as horses or humans.

About 80% of people get no symptoms after infection, 20% get mild symptoms such as fever and flu-like symptoms. Only a very small proportion (1%) develop serious illnesses such as encephalitis or meningitis. With these serious illnesses, the risk of death is 4 to 14%. In people aged 70 years or older, this can increase to 15 to 29%, according to the RIVM.

The virus is not transmitted ‘under normal circumstances’ from person to person, according to the RIVM, only through, for example, blood transplantation.


The West Nile virus has spread to large parts of the world, including south-eastern and central Europe and Germany, in recent decades.

The common whitethroat is a breeding bird. Grass sparrows arrive in April and leave for Africa in late summer. Because the common whitethroat warbler tested positive in the summer, it is very likely that this sparrow caught the virus in the Netherlands, according to RIVM. The same bird was also caught and tested negative in the spring.


Virologist Ab Osterhaus mentioned the virus in February, when the new coronavirus emerged, as an example of how viruses spread. Within a day, we could be on the other side of the world, with a virus among its members. Not only the transport of people, but also the transport of animals or animal products can transmit viruses. Think of the West Nile virus, which was brought from the Middle East to America at the turn of the last century – probably by mosquitoes in the hold of an aeroplane