Tick-borne encephalitis, or TBE

Symptoms of tick-borne encephalitis

The incubation period for tick-borne encephalitis varies from about 7 to 28 days. The European type of virus often has a biphasic course. Approximately 10–30% of infected people develop first-phase symptoms, and approximately one in three develop more severe second-phase symptoms. TBE infections can therefore be asymptomatic.

Initially, the symptoms of tick-borne encephalitis may be vague and resemble a cold. Typical first-phase symptoms include a fever, headache and joint pain. The symptoms of the first phase last about a week, after which most people recover and get lifelong immunity.

Inflammation of the brain can develop if the disease progresses to the second phase. Typical symptoms of the second phase include a fever, headache, neck stiffness and nausea. Other neurological symptoms such as impaired consciousness, seizures or symptoms of paralysis may also occur.

Typical symptoms of tick-borne encephalitis include:

• Fever
• Headache
• Joint pain
• Muscle pain
• Tiredness
• Feeling vague, symptoms of a cold
• Neck stiffness
• Nausea
• Neurological symptoms such as impaired consciousness, seizures or symptoms of paralysis

If tick-borne encephalitis progresses to the second phase, you should seek treatment. If left untreated, tick-borne encephalitis can cause damage to the brain, long-term symptoms or even be life-threatening.

When should I see a doctor if I suspect a tick-borne encephalitis?

Suspected tick-borne encephalitis always requires a doctor’s assessment, especially if the symptoms are severe or neurological. A remote appointment may be sufficient for the initial assessment of symptoms, but an in-person appointment with a doctor is recommended if the symptoms worsen or if you would like to confirm the diagnosis.

See a doctor if:

• you develop high fever
• you have a severe headache
• you have a stiff neck
• you experience severe nervous system symptoms such as impaired consciousness, seizures or symptoms of paralysis

How to diagnose tick-borne encephalitis

Tick-borne encephalitis is diagnosed with blood tests for TBE virus antibodies and antibodies of class IgM. The presence of TBE antibodies indicates that you have been exposed to the TBE virus.

Treatment of tick-borne encephalitis

Treatment of tick-borne encephalitis is mainly symptomatic, as there is no cure for the virus. The aim of the treatment is to alleviate symptoms and prevent the development of complications.

Mild symptoms can be treated at home with painkillers, fever-lowering medication, rest and hydration. In severe cases, the patient may require hospital and supportive care, such as hydration or breathing assistance.

Treatment options for tick-borne encephalitis include:

• Painkillers
• Fever-lowering medication
• Rest
• Hydration
• In severe cases, hospital and supportive care

Tick-borne encephalitis prognosis and mortality

The majority of people with TBE do not develop any symptoms at all, and most of them recover completely. The mortality rate for tick-borne encephalitis is approximately 0.5–1%.

Some people may suffer from long-term or permanent symptoms. These symptoms are similar to those of a brain injury and vary depending on where in the brain the inflammation has caused damage.

Tick-borne encephalitis can have the following later symptoms:

• Memory impairment
• Balance problems
• Hearing loss
• Headache
• Difficulties with concentration
• Paralysis

The chronic form of tick-borne encephalitis is rare but may affect treatment options and require long-term monitoring.

TBE risk areas and prevalence in Finland

The prevalence of tick-borne encephalitis has increased in recent decades. The proportion of TBE carriers among ticks varies greatly from region to region, but is usually around 1–2%. Tick bites do not always lead to an infection, but the risk of infection exists especially in areas with a high prevalence and increases when moving around in nature.

Tick-borne encephalitis occurs particularly in the Åland Islands and the southwest coast, as well as in Uusimaa and the border regions of southeastern Finland. TBE is more common in certain geographical areas and in terrains where ticks thrive. Regional differences are partly due to geographical and climatic factors that affect the habitat and activity of ticks.

Regionally, the TBE virus is most common in:

• The Åland Islands
• The Turku Archipelago
• Uusimaa
• Southeast Finland
• Kymenlaakso

Individual cases of tick-borne encephalitis are also possible in other coastal areas. The number of infections, however, is probably significantly higher than the number of diagnosed cases.

TBE virus and transmission of tick-borne encephalitis

The TBE virus belongs to the group of flaviviruses and its biological properties make it dangerous. The virus is able to penetrate the central nervous system and, in the worst case, can cause encephalitis.

The effective transmission of the TBE virus via ticks is due to the virus’ ability to persist in the tick’s salivary glands, from where it is transferred to animals or humans when biting. Infection occurs within minutes. Also nymphs and larva, the early stages of tick development, can spread the virus in connection with a blood meal, which they need to progress to the next stage.

Tick-borne encephalitis infection can also spread through the unpasteurised milk of cows, goats and sheep who are infected with the disease. Eating and drinking unpasteurised dairy products should be avoided in the risk areas.

Prevention of tick-borne encephalitis

Since the TBE virus spreads within minutes of a tick bite, tick-borne encephalitis is best prevented with protective clothing, an effective insect repellent and a TBE vaccine. Performing a tick check after moving around in nature also helps to prevent tick bites.

Preventing tick-borne encephalitis:

• TBE vaccine: The TBE vaccine prevents approximately 90% of tick-borne encephalitis infections. The vaccine is administered in a series of three doses and booster doses are recommended at regular intervals. Tick vaccinations are free of charge in high-risk areas. Read more about the Finnish Institute for Health and Welfare’s recommendationsExternal link.
• Protective clothing: Clothing plays a significant role in preventing tick bites. Wear long-sleeved shirts and long trousers. Clothing should be light to make it easier to spot ticks. In addition, it’s a good idea to tuck your trouser legs into your socks and wear high-shaft boots.
• Tick checks: Check skin and clothing for ticks after outdoor activities. Also check the coat of any pets, as they can carry ticks indoors.
• Tick repellent: Use tick repellents on bare skin.
• If possible, avoid tick areas: Avoid moving in terrain where ticks thrive. Such humid and vegetative terrains include bogs, field edges, tall grass and bushes.