Tick-borne encephalitis

Introduction

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?

TBE is rarely seen in travellers from the UK. There have been no reported cases brought into the UK since 2006.

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 TBA only have mild symptoms and make a full recovery without treatment.

Recovery from second-stage TBE (see Tick-borne encephalitis – Symptoms) 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.

Last updated: 14 March 2012

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