What is the TBE virus?

The TBE virus is transmitted by ticks and can cause inflammation of the brain, meninges and spinal cord. You can contract the virus if you are bitten by an infected tick in an area where the TBE virus is present, such as in forests in large parts of Europe, Russia, and certain areas in Central Asia. The virus is not yet very common in the Netherlands.

What are the symptoms of an infection involving the TBE virus?

Most people who are exposed to the TBE virus do not become ill, or experience only mild symptoms. These can include:

• mild fever
• headache
• muscle pain and joint pain throughout the body
• nausea and vomiting
• tiredness

If people become seriously ill, the disease usually progresses in two phases. In the first phase, the patient experiences mild symptoms. This usually lasts about four days. A week later, the second phase begins. At this point, the brain, meninges, and spinal cord can become inflamed (encephalitis, meningitis or meningoencephalitis). These severe symptoms always require hospital admission.

Who can become very ill from the TBE virus?

People who often spend time outdoors are more likely to be bitten by ticks. Examples include people who go for long walks, spend a lot of time gardening, or work in gardens or nature reserves. This means that these people also have a higher risk of exposure to the TBE virus.

Some people have a higher risk of becoming seriously ill:

• people aged 70 years and older
• people with other health conditions, such as high blood pressure or diabetes

How does tick-borne encephalitis spread?

You could contract tick-borne encephalitis if you are bitten by a tick that is infected with the TBE virus. Ticks can become infected with this virus if they bite an animal (such as a deer or rodent) that carries the virus. The time between a bite from an infected tick and the first symptoms is 1 to 2 weeks on average.

In very rare cases, people can also become infected by drinking raw milk or eating cheese made from raw milk. This is only possible if the cow, goat, or sheep that the milk came from is infected with the TBE virus. On average, the time between exposure through milk or other dairy products and illness is usually 3 to 4 days.

How can I prevent tick-borne encephalitis?

There is a vaccine against tick-borne encephalitis. The vaccine offers 95% protection against the disease. You can get vaccinated if you are planning to travel to a country where tick-borne encephalitis is common. The list of countries where it is useful to be vaccinated against the TBE virus is available on the LCR website. You do not need to be vaccinated against TBE in the Netherlands.

It is also important to prevent tick bites whenever possible. Minimise the risk by staying on the paths as much as possible and avoiding tall grass and low bushes. Also wear protective clothing when you go out into nature, such as closed shoes, long trousers and long sleeves. You can apply a tick repellent containing DEET to any exposed skin. These measures reduce the risk of tick bites, but do not offer 100% protection. That is why you should always check for tick bites when you return home after spending time in nature.

If you do get a tick bite, it is important to remove the tick safely as soon as possible. This reduces the risk of infection. However, since the TBE virus is transmitted soon after the bite, quick removal of the tick cannot always prevent tick-borne encephalitis. However, quick removal does help to prevent other diseases transmitted by ticks, such as Lyme disease.

Is there any treatment for tick-borne encephalitis?

There is no medication to treat tick-borne encephalitis. Treatment is mainly focused on relieving the symptoms and supporting the patient.

How common is the TBE virus in the Netherlands and where does it occur?

In the past, the TBE virus was only found in other countries. Since 2016, we know that ticks in certain areas of the Netherlands can also be infected with the TBE virus. These areas include the forested hills of Sallandse Heuvelrug and Utrechtse Heuvelrug.

However, the risk of contracting TBE from a tick bite is very low. That is because very few ticks in the Netherlands are infected with the TBE virus.

The map below shows the areas where the TBE virus has been found. It is important to note that even in these areas, approximately 1 in 1,500 ticks are infected with this virus. That is far fewer than the bacteria that causes Lyme disease, for example, which is found in 1 in 5 ticks. The risk of contracting TBE after a tick bite is much lower than the risk of contracting Lyme disease. Ticks carrying the TBE virus may also be present in locations where TBE has not yet been found.

This map shows the occurrence of the TBE virus in the Netherlands (source: DWHC, WUR, Artemis and NorthTick, December 2022).