West Nile fever

West Nile fever is caused by the West Nile virus, which can be transmitted by various types of mosquitoes. It is usually spread by mosquitoes that become infected when they feed on infected migratory birds. The illness can also be transmitted to other mammals and humans. The transmission mainly occurs between birds; however, in areas where the virus causes birds to become ill, other animals and humans may also become infected after being bitten by a mosquito. Mosquitoes that spread the virus are often active in the evening and at night, but daytime mosquitoes can also transmit it. Ticks may potentially carry and spread the virus, but their role in its spread is not yet fully understood. The virus cannot be transmitted from person to person.

Where does West Nile fever occur?

The virus is present in Africa, the Middle East, West Asia, Europe, South and Central America, North America, and Canada. The presence of the virus is often linked to sick birds, and in some areas, a high number of dead birds is associated with an increased risk of infection. Outbreaks can vary significantly, ranging from a few cases to larger epidemics, as seen in the United States.

What are the symptoms?

In most cases, West Nile fever does not cause severe symptoms. However, in some cases, flu-like symptoms may happen, such as:

• Fever
• Headache
• Muscle pain
• Stomach issues
• Skin rash
• Swollen lymph nodes
• Neurological issues
• Fatigue (as a residual symptom)

How to prevent West Nile fever?

Currently, there is no vaccine available for West Nile fever. The only way to protect yourself is to prevent mosquito bites. It is also wise to stay informed about local news regarding outbreaks of West Nile fever.

More information

Would you like to know more about West Nile fever? Please visit the RIVM information page: West Nile fever| RIVM.