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By Dr Benedict Michael, NIHR Doctoral Research Fellow, Professor Tom Solomon, Chair of Neurological Science, Head of Institute for Infection and Global Health, University of Liverpool, Dr Fiona McGill, Specialist Registrar in Infectious Diseases and reviewed by Katherine Dodd, Specialist Registrar in Neurology
What is Tick Borne Encephalitis?
Tick Borne Encephalitis (TBE) is a type of Encephalitis that is caused by a virus that is spread by ticks. Ticks are small parasites that survive by sucking blood from animals – including humans.
Ticks are the main carriers of the virus. It is also found in small rodents and some larger animals such as sheep and goats. There are three different types of TBE. These are the European, the Siberian and the Far Eastern types. The European type is mainly found in central, eastern and northern Europe. People get TBE mostly in Spring and Summer (it is also sometimes called Russian Spring Summer Encephalitis).
How can you get TBE?
Humans can be infected following a tick bite from 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 you are in risk areas. Occasionally people have been infected after drinking untreated milk from animals such as goats.
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. Therefore walkers, for example, are at an increased risk of getting the disease.
Not all ticks carry the virus but it can be present in up to 10% of ticks in some areas.
TBE occurs in parts of Austria, Germany, southern and central Sweden, France (Alsace region), Switzerland, Norway, Denmark, Poland, Croatia, Albania, the Baltic states (Estonia, Latvia and Lithuania), the Czech and Slovak Republics, Hungary, Russia (including Siberia), Ukraine, some other countries of the former Soviet Union, and northern and eastern regions of China. It is predicted that the areas affected will grow due to global warming.
What are the symptoms of TBE?
Most people who are infected with the Tick Borne Encephalitis virus actually show no symptoms at all. In those that do have symptoms they typically appear about 1-2 weeks after the bite. It can be as short as 4 days and as long as 4 weeks. About one third of patients will not have even noticed the tick bite.
In the European type of TBE there are normally 2 phases to the illness. The first phase occurs when the virus is in the blood stream. This phase consists of flu like illness with symptoms such as fever, headache and generalised body aches. It lasts around 5 days. There is then about a week with no symptoms which is followed by the second phase of the illness. The second phase is where the brain or nerves are involved. The severity of the second phase varies between patients. Some people will have a very mild illness whilst others may die. Older people tend to get more severe illness than younger people or children.
The symptoms in the second stage are similar to other causes of Encephalitis and Meningitis (inflammation of the lining of the brain). These include neck stiffness, headache, drowsiness, poor coordination and tremor. Some patients will also get limb weakness (most often in the arms). In severe cases the muscles that control the breathing are affected and people may die.
What tests can be done to diagnose TBE?
Pictures of the brain using CT (computerised tomography) scans or MRI (magnetic resonance imaging) will be done as in other causes of Encephalitis. A lumbar puncture (sometimes called a ‘spinal tap’) will also be done to examine the fluid that surrounds the brain. These tests are helpful to diagnose Encephalitis but are not specific for TBE. However, there is a blood test that can be done specifically for TBE.
What are the consequences of TBE?
Some people (less than 2%) may die from TBE. (This is more common in the Far Eastern type). Most people will recover completely. Still others may have long lasting disability such as paralysis (the inability to move your arms and/or legs). Long-lasting paralysis may occur in up to 6% of people with TBE.
Between 10 and 20% of people will suffer from other complaints such as headache, tiredness, difficulty concentrating and poor memory for at least a year after the illness.
What treatment is available for TBE?
Unfortunately there is no specific treatment for TBE. For people who have severe disease they may need supportive treatment in hospital such as intensive care. However most people will only need symptom control.
TBE can be prevented by avoiding the areas where the disease occurs. If that is not possible then there is also a vaccine available for people who live in highly endemic areas, or travellers to those areas. It is an inactivated vaccine, does not contain live organisms and cannot cause the disease against which it protects. If walking in affected wooded or rural areas it is recommended to wear long trousers to cover exposed skin, use an insect repellent that is effective against ticks, and inspect your skin for ticks regularly. Unpasteurised dairy products should also be avoided in these areas.
Other sources of information:
Tick Alert aims to raise awareness about the risk of Tick Borne Encephalitis (TBE) which is endemic in 27 countries across Europe. The campaign encourages travellers planning to visit a TBE endemic country to find out more about the disease and take action by contacting their GP or travel health clinic to discuss precautions.
The group comprises internationally recognised experts from endemic regions. They work together to raise awareness at both national and international level
FS011V2Tick Borne Encephalitis Page Created: January 1999 /Last Updated January 2014/ Review date: June2017
A multi-disciplinary Steering Committee of experts, including Society Chief Executive, Ava Easton, has called on the European Parliament to take action against the spread of tick-borne diseases in Europe. In the first ever report of its kind, the Putting Tick-borne Diseases on the Map: Reporting the Reality of Tick-borne Diseases Across Europe Steering Committee calls on policy makers, clinicians, travel and tour operators and employers to exercise their responsibilities to people at-risk of contracting tick-borne diseases. Through awareness, prevention and accurate diagnosis and reporting, these stakeholders can help to combat the growing risk posed by tick-borne diseases across Europe.
Tick-borne diseases, including tick-borne Encephalitis and Lyme borrelliosis, are the most common vector-borne diseases in Europe. Despite this, and the danger that they pose to the public health environment, awareness of these diseases and methods to prevent exposure vary widely across Europe. The Putting Tick-borne Diseases on the Map: Reporting the Reality of Tick-borne Diseases across Europe report seeks to address this variability one year on from the European Commission’s decision to make tick-borne encephalitis a notifiable disease, meaning that any cases diagnosed in Europe must be reported to the relevant health authorities.
"Encephalitis is a thief." said Ava Easton, member of the Steering Committee and Chief Executive of the Encephalitis Society. "It robs people of things that most of us take for granted - personality, memory, cognition, occupation, family. It robs families of their lived ones and even in families where those affected survive, they experience a complicated form of bereavement for the person they once knew. We all have a duty to protect people from unknowingly inviting encephalitis into their lives.”
The Steering Committee’s calls to action are underpinned by a survey of over 700 individuals at-risk of contracting a tick-borne disease. This survey confirms that awareness of the risks posed by tick-borne diseases vary widely across Europe. Moreover, the survey suggests that people may be putting themselves at-risk of contracting a tick-borne disease because they are unaware of effective methods of prevention, including the use of repellents, protective clothing and vaccination.
The full report can be found here.
The Encephalitis Society is the operating name of the Encephalitis Support Group which is a registered Charity and Company Limited by Guarantee.
Registered in England and Wales No. 4189027. Registered Office as above. Registered Charity No. 1087843.