Tick-borne encephalitis

Tick-borne encephalitis (TBE) is a viral infection spread to humans by the bite of a small spider-like parasite called a tick.

Initial symptoms of TBE are similar to flu and can include:

• a high temperature (fever)
• a headache 
• tiredness 
• muscle pain

These symptoms usually last for up to eight days, after which point most people make a full recovery.

However, some people will go on to develop more serious symptoms caused by the virus spreading to the layer of protective tissue that covers the brain and spinal cord (meningitis) or the brain itself (encephalitis).

These ‘second-stage’ symptoms can include:

• changes in mental state, such as confusion, drowsiness or disorientation
• seizures (fits)
• sensitivity to bright light (photophobia)
• an inability to speak
• paralysis (inability to move certain body parts)

If TBE reaches this stage, you will usually need to be admitted to hospital. These symptoms tend to get slowly better over a few weeks, but it may take several months or years to make a full recovery and there is a risk you could experience long-term complications (see below).

Around one in every 100 cases of TBE is fatal.

Read more about the symptoms of tick-borne encephalitis.

When to seek medical help

If you have returned from a part of the world known to have cases of TBE and you begin to experience flu-like symptoms, you should contact your GP for advice.

You should seek medical advice as soon as possible if you have been bitten by a tick in a risk area (see below) and you haven't been vaccinated against TBE, or if you develop a rash or fever after being bitten.

The advanced stages of TBE need emergency treatment in hospital. Call 999 (or the equivalent number where you are staying) immediately and ask for an ambulance if you have flu-like symptoms that are getting rapidly worse and are affecting your mental state.

Risk areas

Ticks that spread the TBE virus are not found in the UK. They are mainly found in rural areas of central, northern and eastern Europe.

There are also two sub-types of TBE found in eastern Russia and in some countries in East Asia, particularly forested regions of China and Japan.

See the Tick Alert and National Travel Health Network and Centre (NaTHNaC) websites for maps showing the areas where infected ticks are found.

How the infection is spread

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

You can become infected with TBE if you are bitten by an infected tick. The virus is present in the tick’s saliva, which also contains a natural anaesthetic so you may not notice you have been bitten.

You can be bitten by an infected tick at any time of year, but tick activity is at its highest during the Spring and early Summer. 

Rarely, eating and drinking unpasteurised milk and dairy products from infected animals, especially goats, can expose you to the TBE virus.

How common is tick-borne encephalitis?

There have been very few cases of TBE reported in the UK, with only around 12 cases diagnosed between 2011 and 2013.

However, the condition is relatively common in areas where infected ticks are found, so it's important to take steps to reduce your risk of infection (see below).

The World Health Organization estimates that between 10,000 and 12,000 cases of TBE are reported worldwide each year, although the actual number of cases is believed to be much higher than this because it is likely many cases are not reported.

Preventing tick-borne encephalitis

The best way to prevent TBE is to be vaccinated against the infection before you travel if you are planning to work or travel in a part of the world where there is a risk of TBE, particularly if you are planning to visit rural areas or go hiking or camping.

The vaccine, which is only available privately, provides protection against TBE in around nine out of every 10 people who receive it.

Even if you have been vaccinated, you should still take precautions to reduce your risk of being bitten by an infected tick, such as:

• wearing long-sleeved tops and trousers tucked into your socks
• applying insect repellent containing DEET to exposed skin
• checking your body for ticks regularly – common places to find them are the hair line, behind the ears, the elbows, backs of the knees, the groin and the armpits

Read more about preventing tick-borne encephalitis.

How tick-borne encephalitis is treated

If a doctor thinks you may have TBE, they will perform a blood test or lumbar puncture (where a sample of spinal fluid is removed) to confirm whether you are infected.

There is currently no cure for TBE, so treatment aims to help relieve symptoms until the infection passes.

If you only experience the initial symptoms of TBE, no treatment is required other than taking painkillers such as ibuprofen or paracetamol to help relieve your symptoms.

If you develop second-stage symptoms, you will usually be admitted to hospital. Hospital treatment involves providing supportive treatments such as fluids into a vein (intravenous fluids), help with breathing and nursing care. 

Read more about treating viral meningitis and treating encephalitis.

Possible complications

If you develop second-stage symptoms caused by the infection spreading to the brain, there is a risk you could experience long-term (and possibly permanent) complications, such as:

• memory problems
• problems with concentration and a short attention span
• changes in behaviour, such as becoming more impulsive and having poor judgement

These sort of long-term effects occur in more than one in 10 people who develop symptoms of TBE.

Read more about the complications of tick-borne encephalitis.