Netherlands reports rise in West Nile virus cases and deaths

21:50

By: Azzat Manal

Netherlands reports rise in West Nile virus cases and deaths

The Netherlands is reporting a rise in West Nile virus infections, with health authorities closely monitoring the spread of the mosquito-borne disease across several parts of the country. The latest figures indicate that infections have been detected among people as well as birds, mosquitoes and horses.

According to the National Institute for Public Health and the Environment (RIVM), West Nile virus is primarily maintained in a cycle involving birds and mosquitoes. Infected mosquitoes can occasionally transmit the virus to humans and other mammals, including horses. Human infections are generally acquired through mosquito bites, while transmission between people is not considered a normal route of infection.

Dutch authorities have expanded surveillance as the virus has been detected in multiple provinces. The RIVM has been working with doctors, veterinarians, virologists, epidemiologists and ecologists to track the virus and assess its development. Monitoring includes testing in humans, mosquitoes, birds and horses.

Most people infected with West Nile virus experience no symptoms. The RIVM estimates that around 19% of infected people develop relatively mild, flu-like symptoms, which can include fever, headaches and muscle pain. In a small proportion of infections, however, the disease can affect the nervous system and lead to serious conditions such as encephalitis or meningitis.

The current situation has also prompted attention to blood safety. The RIVM has noted that, although person-to-person transmission does not normally occur, rare cases can involve blood transfusions or organ donations. Sanquin, the Dutch blood supply organization, has therefore been conducting additional screening in areas where West Nile virus has been detected.

West Nile virus was first identified as a locally acquired human infection in the Netherlands in 2020. After several years without confirmed human infections acquired in the country, the virus was detected again in 2026, prompting renewed surveillance during the mosquito season.

The presence of the virus in animals has also become an important part of the monitoring effort. Birds play a central role in the virus's natural transmission cycle, while mosquitoes act as the main vectors. Horses and humans can become infected through mosquito bites but do not normally transmit the virus onward.

Dutch health authorities are continuing to monitor the situation and encourage measures aimed at reducing exposure to mosquito bites. While severe illness remains uncommon, older adults and people with reduced immunity are considered more likely to develop serious complications following infection.

The renewed detection of West Nile virus in the Netherlands reflects a broader need for coordinated surveillance of diseases transmitted by mosquitoes. Dutch authorities are continuing to combine human health data with information from animals and the environment to identify potential changes in transmission and respond accordingly.