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Tick-borne Encephalitis

Tick-borne encephalitis (TBE) is a potentially fatal viral infection of the central nervous system transmitted mainly through the bite of infected ticks. It occurs in an endemic region spanning from eastern Europe all the way into China, and includes 27 European countries and a number of Asian countries. An estimated 10,000 - 12,000 cases of TBE are reported worldwide each year [53].

How is it contracted?
You can become infected with TBE if you are bitten by an infected tick, and less commonly through drinking unpasteurised milk from infected animals, especially goats. The virus is present in the tick’s saliva, which also contains a natural anaesthetic so you may not notice you have been bitten. Ticks usually live in the undergrowth in rural areas and most human infections are contracted during outdoor leisure pursuits such as: forestry working, camping, rambling and mountain biking. You can be bitten by an infected tick at any time of year, but most cases are reported between Spring and Autumn when there is increased exposure to the tick vector. 

Signs and symptoms
The incubation period is usually 7-14 days from being bitten by an infected tick [50] and symptoms present in two stages. The first stage is characterised by a non-specific flu-like illness with fatigue, headache, myalgia, nausea, general malaise and fever.  About a third of these patients then enter a second more severe phase, caused by the virus spreading to the layer of protective tissue that covers the brain and spinal cord (viral meningitis) or the brain itself (encephalitis). This is characterised by a sudden rise in temperature  [51], along with changes in mental state, such as: confusion, seizures, sensitivity to bright light, inability to speak and paralysis. 

In the majority of patients the disease resolves spontaneously, although it may take patients with second stage symptoms several months or years to make a full recovery, and some patients require long term rehabilitation. In children, severe disease is usually limited to inflammation of the tissues surrounding the brain (viral meningitis), whereas people over 40 years have a higher chance of developing infection of the brain itself (encephalitis): in up to 40 percent of these cases the disease results in permanent central nervous system damage. Fatality is dependent on age and also the virus subtype. People over 60 years of age are more likely to die from the disease, while the Far Eastern subtype has a reported fatality rate of more than 20%, the Siberian subtype of 6-8%, and the European subtype of 1-2% [51].

There is no specific treatment for TBE and management relies on supportive care with serious disease usually requiring hospitalisation. 

Recommendations for Travellers
The best form of prevention is avoiding being bitten by protecting the skin with clothing, tucking long trousers into socks, using insect repellents and avoiding undergrowth by using designated pathways. If a traveller is bitten by a tick in an area of risk for TBE, they should remove the whole tick with tweezers as soon as possible. The tick should not be squeezed as that may potentially deliver more virus into the body. If any signs of illness occur within 28 days of a tick bite, advice should be promptly sought from a medical practitioner. An effective vaccine is available, and travellers should consider being vaccinated against TBE if they are at risk of tick bites in endemic areas.

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Tick-borne Encephalitis. Here’s the point...

The disease, which can be very serious, is thought to be considerably under reported and the condition is relatively common in areas where infected ticks are found, so vaccination is recommended to those considered to be at high risk.