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Tick-borne encephalitis

 

Tick-borne encephalitis (TBE) is a viral infection of the central nervous system (brain and spinal cord) that is spread by tiny blood-sucking parasites called ticks.

TBE can cause: 

  • encephalitis (inflammation of the brain)
  • meningitis (inflammation of the membranes that surround the brain and spinal cord)
  • other serious problems with the nervous system

For more information on symptoms, see Tick-borne encephalitis - Symptoms

Types of TBE

There are three main types of TBE:

  • Western European - found in the forested areas of central, eastern and northern Europe, including Austria, Bosnia-Herzegovina, Croatia, Estonia, Latvia, Czech Republic, Slovakia, Germany, Hungary, Macedonia, Montenegro, Poland, Serbia, Slovenia, Switzerland, Russia and Ukraine
  • Far Eastern - found in eastern Russia during spring and summer and in some countries in East Asia, particularly forested regions of China and Japan
  • Siberian - found in Siberia

How it is spread

The TBE virus is found naturally in small animals such as mice and voles and in domestic animals such as sheep, goats and cattle. Ticks are the main carriers of the virus, picking up the virus when they feed on the blood of an infected animal. Once the tick is infected with the virus, it carries this for life.

Humans become infected with TBE when they are bitten by an infected tick. The virus is present in the tick's saliva, which contains a natural anaesthetic, so you may not notice you have been bitten. It is important to check your body regularly for ticks when in risk areas.

Where ticks are found

Ticks live in forests, woods, grasslands, riverside meadows, marshes, brushwood and shrublands. They usually live in the undergrowth, where they can easily get onto the clothes or skin of passers-by.

Tick activity depends on factors such as temperature, moisture and humidity. Wet summers and mild winters increase tick activity. In central Europe the main periods of tick activity are May/June and September/October. In the mountainous and colder areas of northern Europe, ticks only tend to be active in summer and are rarely found in areas above 1,000 metres.

Very rarely, unpasteurised milk from infected animals, especially goats, can also carry the TBE virus.

How common is it?

The risk of infection with TBE after a single tick bite varies between 1 in 200 and 1 in 1,000, depending on the area you visit. Check with a travel health clinic for the level of risk in the area you are planning to travel to.

Outlook

Most people infected with TBE only have mild symptoms and make a full recovery without treatment.

Recovery from second-stage TBE is a much longer process and there may be permanent damage to your nervous system. Some people go on to develop other long-term neurological conditions, such as memory problems or epilepsy.

TBE is very rarely fatal: only 1-2% of cases end in death.

A bite from an infected tick can result in inflammation of the brain (encephalitis)

Who is at risk

  • You may be at risk if you are planning to walk, camp or work in woods and forests in areas where infected ticks are likely to be found.
  • You may also be at risk if you eat or drink unpasteurised dairy products from infected cows, goats or sheep, but this is very rare.

Symptoms of tick-borne encephalitis (TBE) occur in two stages.

Stage one

The initial symptoms of TBE usually occur 7-14 days after a tick bite. Two-thirds of people infected with TBE get these symptoms, while the other third will have no symptoms.

Symptoms include:

  • fever (temperature of 38C (100.4F) or above)
  • headache
  • flu-like illness
  • tiredness
  • muscle pain
  • nausea

These first-stage symptoms usually last between one and eight days. After this, there are no symptoms for the following 1-20 days. Around one-third of those who experience first-stage symptoms go on to develop the second phase of the disease.

Stage two

The second phase of the disease starts with a sudden rise in temperature. The virus starts to affect your central nervous system (brain and spinal cord), which can result in meningitis (inflammation of the membranes surrounding the brain and spinal cord) and encephalitis (inflammation of the brain). These conditions can cause paralysis.

In the second stage of illness, children usually develop meningitis. Around one-third of people who experience second-stage symptoms will develop encephalitis. Adults over the age of 40 are particularly vulnerable to encephalitis. There is a higher risk of death in people over the age of 60.

Symptoms of meningitis

Most people with viral meningitis will have mild, flu-like symptoms such as:

  • headaches
  • fever (temperature of 38C (100.4F) or above)
  • chills
  • muscle or joint pain

In severe cases of viral meningitis, symptoms can also include nausea, vomiting and an intolerence to bright light (photophobia).

For more information on meningitis symptoms, see the Health A-Z page on Meningitis - Symptoms

Symptoms of encephalitis

Encephalitis also usually begins with flu-like symptoms, such as a headache and generally feeling unwell.

More serious symptoms follow over the space of a few hours or days. These include:

  • a high temperature (38C (100.4F) or above)
  • nausea
  • vomiting
  • changes in mental state, such as confusion
  • drowsiness or disorientation
  • seizures (fits)
  • aversion to bright lights (photophobia)
  • inability to speak
  • inability to control physical movements
  • stiff neck
  • uncharacteristic behaviour, such as being unusually aggressive

 

When to call 999

Second-stage symptoms of TBE need to be treated in hospital. Flu-like symptoms that rapidly get worse and change a person’s mental state should be treated as a medical emergency. Call 999 and ask for an ambulance.

If a doctor thinks you may have tick-borne encephalitis (TBE), they will ask you about your symptoms, medical history, where you have been travelling and if you think you may have been bitten by a tick.

They will then test your blood for antibodies to the virus. Antibodies are proteins produced by your immune system to fight infection. If antibodies are found, you may need to have further tests to confirm the results.

Further tests may include:

  • an MRI scan (brain scan to check for signs of inflammation indicating encephalitis) 
  • a lumbar puncture, where a sample of your spinal fluid is checked for the TBE virus and signs of inflammation of the membranes covering the brain and spinal cord

What to do if you think you have been infected…

 

  • If you are travelling in countries where TBE is found and are bitten by a tick, remove it with tweezers as soon as possible (seeTick-borne encephalitis – Prevention  for further advice on removing ticks).
  • If you start to experience any symptoms within 28 days of a tick bite, contact a doctor or health clinic as soon as possible.
  • If you start to experience symptoms after you return home and think you may have been bitten by an infected tick while travelling, contact your doctor as soon as possible.

If you are infected with tick-borne encephalitis (TBE) and do not experience any symptoms, or only experience mild first-stage symptoms, you will usually get better without treatment. Paracetamol can be taken to relieve any flu-like symptoms.

In cases of stage-two TBE, there is no specific drug treatment. For severe symptoms such as meningitis and encephalitis, you need to go to hospital where you will be given supportive treatments such as intravenous fluids, help with breathing and nursing care to support your body while you recover.

If you develop encephalitis, you will probably be admitted to an intensive care unit (ICU), where doctors will aim to:

  • stop and reverse the process of infection using medication
  • control any complications, such as seizures or dehydration
  • prevent long-term complications such as memory loss or epilepsy

Tick-borne encephalitis (TBE) can be prevented by:

  • having a vaccination against TBE 
  • avoiding tick bites when in risk areas

Vaccination

A vaccination is the best way to prevent TBE for people living, working or travelling in risk countries. You may consider having the TBE vaccination if:

  • You are living in or planning to move to a risk country.
  • Your work puts you at risk of TBE (for example, if you are a farmer, forestry worker or soldier).
  • You are planning to travel to a risk area during late spring or summer and will be taking part in activities that put you at risk, such as camping, hiking or bird watching.

The best time to start a course of TBE vaccination is during the winter months to make sure you are protected before the start of the tick season in spring. Your doctor may be able to order the TBE vaccine for you from a specialised travel clinic, but you will still have to pay for the course of vaccine. You may prefer to go directly to a travel health clinic.

Vaccination course

The TBE vaccine is usually given in three doses, with the second dose given one to three months after the first dose, and the third dose given five and 12 months after the second dose. If you need more urgent protection, two doses of the vaccine can be given at least two weeks apart. In this case, the third dose should be given five to 12 months after the second dose. If you are under 60, you should have your first booster three years after your original course of the vaccine. Further boosters should be given every three to five years. If you are over 60, you should have booster doses every three years. This is because studies have shown that TBE immunity (resistance) does not last as long in older people.

Side effects

Any reactions to the TBE vaccination are usually mild and do not last long. Adults may experience swelling, redness and pain at the site of the injection. Other possible side effects include tiredness, headache, muscle pain and nausea.

Children usually experience mild side effects such as pain and tenderness at the site of injection, restlessness and headache. They may also experience a fever (temperature of 38C (100.4F) or above) after their first dose of the vaccine. In very rare cases, a more serious reaction can cause meningitis.

Precautions

You should not have the vaccination if:

  • You are allergic to eggs (as the vaccine contains egg protein). 
  • You have a fever.

You must also tell your doctor or nurse if any of the following apply to you:

  • You have problems with your immune system.
  • You have a brain disorder.
  • You are pregnant.
  • You are breastfeeding.

You may still be advised to have the vaccine, but your doctor or nurse will need to check your risk with a travel medicine specialist before giving it to you.

Protecting yourself

The best way to lower your risk of TBE is to avoid tick bites as much as possible when in risk areas:

  • Wear long-sleeved tops and long trousers (tucked into socks). You can treat your clothes with insecticides such as permethrin.
  • Apply insect repellent containing DEET to any exposed skin.
  • Check your body for ticks regularly. Common places to find them are the hair line, behind the ears, elbows, backs of knees, the groin and armpits.
  • Avoid eating and drinking milk and unpasteurised dairy products in countries where there is a high risk of TBE.

What to do if you find a tick

After a tick has attached itself to you, it may not start feeding for several hours. Adult ticks, once they have fed, can be up to the size of a coffee bean, but tick larvae can be tiny. If you find a tick on your body, you should remove it as quickly as possible with a pair of tweezers or tick remover:

  • Place the tweezers as close as possible to your skin and pull the tick off very firmly and slowly until the tick lets go of your skin (make sure you remove its head and mouth).
  • Avoid squeezing the body of the tick and the contents of its stomach into the site of your bite.
  • After you have removed the tick, wash your hands and the affected area with soap and water.

Is DEET safe?

The chemical DEET (diethyltoluamide) is commonly used in insect repellents.

It is not recommended for use on children under two months old.

It is safe for older children, adults and pregnant women when used according to the manufacturer’s instructions:

  • Use on exposed skin.
  • Do not spray directly onto your face, but spray into your hands and pat onto your face.
  • Avoid contact with lips and eyes.
  • Wash hands after applying.
  • Do not apply to cuts, abrasions or broken or irritated skin.
  • Avoid sunscreen containing insect repellent.
  • Wash off repellent when you are no longer exposed to insects.

European Health Insurance Card (EHIC)

Always make sure you take out adequate travel insurance for the countries you are visiting. If you are travelling in Europe, get a European Health Insurance Card (EHIC) as well as travel insurance.

An EHIC is free, and it could save you money and hassle if you need medical help while you are away. It allows you to access state-provided healthcare in all European Economic Area (EEA) countries and Switzerland at a reduced cost or sometimes free.

For more information, visit EHIC


Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.