Tick-borne encephalitis (TBE) is a viral infection spread to humans by the bite of a small spider-like parasite called a tick.
It's a rare infection that's only acquired abroad in certain European and Asian countries (see 'Risk areas' below).
Initial symptoms of TBE are similar to flu and can include:
These symptoms usually last for up to eight days, after which point most people make a full recovery.
However, some people go on to develop more serious symptoms caused by the virus spreading to the protective layer of 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)
- being unable to speak
- paralysis (inability to move certain body parts)
If TBE reaches this stage, you'll 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's 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
Contact your GP if you've returned from an area of the world known to have cases of TBE (see below), and you start to experience flu-like symptoms.
You should seek medical advice as soon as possible if you've been bitten by a tick while in a risk area 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're staying) immediately and ask for an ambulance if you have flu-like symptoms that are getting rapidly worse and affecting your mental state.
The TBE virus isn't present in the UK, so there's no risk of infection within the UK. However, cases of infection can occur among travellers returning from countries within Europe and Asia where TBE-infected ticks are found.
Infected ticks 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.
Visit Travel Health Pro for a map showing the areas where infected ticks are found.
How the infection is spread
Ticks are found in forests, woods, grasslands, riverside meadows, marshes, brushwood and scrublands. They usually live in the undergrowth, where they can easily get onto people's clothes or skin.
You can become infected with TBE if you're 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've 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.
Drinking unpasteurised milk and eating unpasteurised dairy products from infected animals, particularly goats, can expose you to the TBE virus. However, this is rare.
How common is tick-borne encephalitis?
Very few cases of TBE have been reported in the UK, with just nine cases diagnosed in 2013/14.
However, TBE is fairly 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 (WHO) estimates that between 10,000 and 12,000 cases of TBE are reported worldwide each year. However, the actual number of cases is thought to be much higher than this because it's likely that many cases aren't reported.
How tick-borne encephalitis is treated
If a doctor thinks you may have TBE, they'll carry out a blood test or lumbar puncture (where a sample of spinal fluid is removed) to confirm whether you're infected.
There's 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.
You'll usually be admitted to hospital if you develop second-stage symptoms. In hospital you'll receive fluids into a vein (intravenous fluids), help with breathing and nursing care.
Read more about treating viral meningitis and treating encephalitis.
If you develop second-stage symptoms of TBE caused by the infection spreading to the brain, there's a risk you could experience long-term (and possibly permanent) complications, such as:
- memory problems
- problems concentrating and a short attention span
- behavioural changes, such as becoming more impulsive and having poor judgement
These types 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.
Preventing tick-borne encephalitis
The best way to prevent TBE is to be vaccinated against the infection before you travel if you're going to be working or travelling in a part of the world where there's a risk of TBE, particularly if you're 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've been vaccinated, you should still take precautions to reduce your risk of being bitten by an infected tick. For example, you should:
- wear long-sleeved tops and trousers tucked into your socks
- apply insect repellent containing DEET to exposed skin
- regularly check for ticks – common places to find them are around the hair line, behind the ears, on or around the elbows, the backs of the knees, the groin and the armpits
Read more about preventing tick-borne encephalitis.
Ticks in the UK
You should also be aware that tick bites can spread other illnesses, such as Lyme disease, which you can get after being bitten by a tick in the UK. Therefore, follow the advice above to avoid tick bites when you and your family are in areas of the UK where ticks are commonly found.