What is Tick-Bourne Encephalitis?

Tick-borne encephalitis (TBE) is a viral infection that is transmitted predominantly through the bite of an infected Ixodes tick. TBE virus belongs to a closely related group of viruses called flaviviruses. These include yellow fever, dengue and Japanese encephalitis. There are five subtypes of TBE virus, the three main ones are: European/Western, Siberian and Far Eastern.

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TBE affects the central nervous system and may cause a spectrum of disease, from a mild short-lived illness to a more severe life-threatening illness with the potential for severe neurological complications. The disease occurs in parts of central, northern and eastern Europe, Siberia and parts of Asia. TBE is rarely fatal in Europe. However in Asia, it may be fatal in up to 20 percent of cases and long-term neurological problems are common.

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Risk Areas

TBE is reported in a band of areas extending from central, eastern and northern Europe, across Russia to parts of eastern Asia, mainly in non-tropical regions of the Eurasian forest steppe. These areas are generally at altitudes lower than 1500 metres. However, ticks have been noted at higher altitudes. Climate change is thought to have resulted in TBE risk areas moving northward and to higher altitudes.

 

Transmission

TBE is usually transmitted through the bite of an infected Ixodes tick, the main vectors of TBE virus. The virus is maintained in nature by a number of animal ‘hosts’ including; small mammals (mice and voles), domestic livestock (sheep, goats and cattle) and certain bird species. Human infection occurs incidentally, when individuals encroach on areas where the virus is present and are inadvertently bitten by infected ticks. Ticks are found on forest fringes within adjacent grassland, forest glades, riverside meadows and marshland, forest plantations with brushwood, and shrubbery. Ticks can also be found in parks and gardens. They tend to reside on ground level vegetation, on the underside of foliage, from where they can be brushed onto clothing. Ticks are capable of transmitting the TBE virus throughout their lifecycle stages (larvae, nymphs or adults) and once infected, carry the virus for life. Tick activity and development are affected by local climatic factors such as temperature, soil moisture and relative humidity.

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Signs and symptoms

Two phases of symptoms are usually seen after infection with European/Western TBE sub-type. Approximately up to 30% of those infected with this sub-type develop a non-specific flu-like illness with fever, fatigue, headache and muscle pain after an incubation period of about eight days (range of 2 to 28 days).

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An interval of 1 to 20 days follows, during which patients usually have no symptoms. After this, approximately one third of those with initial symptoms will progress to the second stage heralded by a sudden rise in temperature, with clinical features of meningitis (inflammation of brain lining), meningoencephalitis (affecting brain and lining) and meningoencephalomyelitis (the most severe form also affecting the spinal cord). ​

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Prevention

If travel to TBE endemic areas during spring, summer and autumn cannot be avoided, travellers should be advised to take risk avoidance measures including:

• Practice bite avoidance methods: for example, wear appropriate clothing and use effective insect repellents.

• Check the whole body for ticks regularly. Larval forms of Ixodes ticks are tiny and difficult to see (they can be the size of a freckle or speck of dirt). After feeding, adult ticks become engorged and can be the size of a coffee bean. Common areas for ticks are armpits, back of knees, elbows, groin and hair-line. However, ticks can attach anywhere, so a full body check is recommended.

• Remove ticks as soon as possible with a pair of fine tipped tweezers or tick remover.

• Avoid consumption of unpasteurised dairy products.

• If any signs of illness occur within 28 days of a tick bite, seek prompt advice from a medical practitioner.

• TBE vaccine is available for those visiting risk areas or individuals whose occupation puts them at higher risk.

 

Side effects

Adverse reactions following TBE vaccine are most commonly mild and transient. In adults they include local reactions such as swelling, redness and pain at the injection site. Generalised reactions such as fatigue, malaise, headache, muscle pain and nausea have been reported but were transient and usually mild.

 

Vaccination Schedule 

TicoVac 0.5ml (16 years +)

3 doses - Primary schedule

• First dose - Day 0

• Second dose - between 1 months and 3 months after first dose

• Third dose - 5-12 months after the second dose

Accelerated schedule

• Second dose can be given 2 weeks after the first dose.

TicoVac 0.25ml Junior (Age 1-16 years)

3 doses - Primary schedule

• First dose - Day 0

• Second dose - between 1 months and 3 months after first dose

• Third dose - 5-12 months after the second dose

Accelerated schedule

• Second dose can be given 2 weeks after the first dose.

 

Protection after the second dose

After the first two doses, sufficient protection can be expected for the on-going tick season (protection rate over 90 percent after the second dose)

Boosters and Long-term Protection

First boosters no more than 3 years after the third dose. After this, boosters maybe given at 5 year intervals if at risk (>60 years boosters should not exceed 3 years)

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Prices 

TicoVac 0.5ml £75/dose

TicoVac Junior 0.25ml £70/dose

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Additional information

For more information, click here