Around two in every three people infected with a tick-borne encephalitis (TBE) virus don't develop any symptoms. However, if symptoms do develop, they can be very serious.
In most cases, the symptoms of TBE develop in two distinct stages.
The initial symptoms of TBE usually develop at some point between two and 28 days after being bitten by an infected tick. Symptoms can include:
These initial symptoms usually last for one to eight days, after which point most people will make a full recovery.
However, after a period of up to three weeks without any symptoms, some people will go on to develop more serious problems.
In the second phase of the infection, the virus starts to affect your central nervous system (brain and spinal cord), which can cause:
- meningitis – inflammation of the membranes surrounding the brain and spinal cord
- encephalitis – inflammation of the brain
Symptoms of meningitis and encephalitis include:
- a sudden fever
- nausea and vomiting
- a stiff neck
- a headache
- changes in mental state, such as confusion, drowsiness, or disorientation
- seizures (fits)
- sensitivity to bright light (photophobia)
- an inability to speak
- personality and behavioural changes
- paralysis (inability to move certain body parts)
If TBE reaches this stage, you'll need to be admitted to hospital. These symptoms usually slowly get better over a few weeks, but it may take several months or years to make a full recovery and more than one in 10 people develop long-term problems.
Around one in every 100 people who develops symptoms of TBE will die as a result of the condition.
Read more about the complications of tick-borne encephalitis.
When to seek medical advice
You should contact your GP if you've returned from an area of the world with a high TBE risk and you start to experience flu-like symptoms.
Seek medical advice as soon as possible if you've been bitten by a tick in a TBE 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 hospital treatment. 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 are affecting your mental state.
Read more about diagnosing tick-borne encephalitis and treating tick-borne encephalitis.