West Nile virus in Belgium: 4 questions, 4 answers
West Nile virus is circulating increasingly widely in Europe, including Belgium. The virus mainly affects birds, but in September 2026, infections were also detected in people in Belgium for the first time. The risk to the general population is still considered very low, but employees who work outdoors a lot may come into contact with mosquitoes more often. What does this mean for your work environment? We’re answering four of your questions.
The figures are updated daily and are available on the European Centre for Disease Prevention and Control website.
1. What is the West Nile virus?
The West Nile virus mainly affects birds and is spread by infected mosquitoes, including the common house mosquito.
Mosquitoes can pass the virus to other mosquitoes and sometimes to people and other mammals, such as horses. An infected person or horse cannot infect new mosquitoes. The virus is not transmitted directly from person to person or from horse to person either.
Therefore, people can only become infected through a mosquito bite, a blood transfusion, or an organ donation.
In very rare cases, the virus can also pass from mother to child during pregnancy, childbirth, or breastfeeding.
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2. How can you recognise an infection?
One in five infected people develops symptoms after 2 to 14 days, such as headache, muscle pain, fever, a rash, and swollen lymph nodes.
Most people recover fully, although fatigue can sometimes last for several weeks or months.
In rare cases (1% of infections), infected people develop a serious illness such as encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes surrounding the brain). Severe illness is more common in older people and can be fatal (in one in ten people affected).
There is no specific treatment for West Nile virus; symptoms are treated with painkillers and rehydration. There is currently no vaccine against West Nile virus for people.
Risk prevention therefore focuses mainly on avoiding mosquito bites.
3. Are my employees at risk?
Do your employees spend a lot of time working outdoors or in places with a high concentration of mosquitoes? If so, be extra vigilant. Examples include construction sites, grounds maintenance, agriculture, nature reserves, water management, outdoor storage, and temporary events or venues.
Pay particular attention to damp, densely vegetated areas and places with standing water.
4. What can I do to protect my employees?
Do your employees work in any of these higher-risk places? Contact your risk prevention advisor to identify the locations and determine the right actions.
Inform your employees about the risk and possible symptoms too.
A few simple risk prevention measures can reduce the risk of infection:
Cover exposed skin.
Wear long sleeves and trousers where possible. Choose work clothing that covers the skin. Pay particular attention to ankles, wrists, and the neck.
Mosquito-repellent or insecticide-treated clothing can provide additional protection during work involving high exposure.
Apply insect repellent to exposed skin. Avoid using too much and follow the guidance on the appropriate concentration of the product.
Remember: repellent supplements protective clothing; it does not replace it.Avoid places with standing water where possible. Do not leave buckets, tubs, gutters, or containers filled with water unnecessarily. Cover waste containers and water reservoirs. Store outdoor equipment (wheelbarrows, construction materials, tarpaulins, etc.) correctly so that water cannot collect in it. Repair leaks and drainage problems.
Where possible, arrange work breaks indoors.
Where possible, make the workplace less accessible to mosquitoes by using fly screens or insect mesh and keeping doors and windows closed.
Need some help?
We can help you identify higher-risk workplaces or update your risk assessment. Contact us via the MyMensura customer portal or through your account manager.
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