What is TBE?

• Tick-borne encephalitis (TBE) is a viral infection affecting the brain and spinal cord, that is mainly spread by tick bites; although, in rare cases, can also be found in unpasteurised dairy products from infected animals.
• TBE is transmitted within minutes from infected tick’s saliva and there is no cure for TBE.
• The disease is caused by the tick-borne encephalitis virus (TBEV), which is a member of the Flaviviridae family of viruses.
• The TBE virus is widespread across at least 27 European countries, Russia and parts of Asia.
• Approximately 10,000–12,000 clinical TBE cases are reported each year, but this figure is believed to be underestimated as notification of the disease is often not mandatory.

Global Distribution of the Tick-Borne Encephalitis Virus (TBEV)

Across the globe, 3 major subtypes of tick-borne encephalitis virus (TBEV) are responsible for most cases of TBE: European, Siberian and Far-Eastern

Adapted from: Lindquist L. Handb Clin Neurol 2014; 123: 531-59

Who is at Risk of TBE Infection?

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Forest visitors are at a 4–5 times higher risk of tick encounters than others.

People spending time outdoors in high risk regions.

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The danger of being infected is highest between April and November in Europe.

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     10–20% of TBE cases are reported in children.

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• In endemic areas, the risk of TBE is greatest for people who partake in recreational activities (e.g. dog owners, golfing, camping, hiking, fishing, gardening and foraging) or occupational outdoor activities (e.g. hunting, woodcutting, forestry, farming and military activities).
• In Europe (including Finland), peak tick activity has been observed between April and November.
• Across all age groups, men are more frequently affected than women and 10–20% of TBE cases are reported in children.
• TBE has become a more global problem due to tourism and should therefore, be considered in the differential diagnosis of CNS infections in those with an appropriate history.

TRANSMISSION

How is TBE Transmitted?

 

The primary reservoirs and hosts of TBE virus (TBEV)  in nature are small rodents (e.g. voles, mice), and transmission to humans via hard tick bites within minutes.

 

Infected ticks may be found in woodland habitats, including deciduous forests and transition zones between forests and grasslands. Infected ticks are also found in city parks and gardens.

 

 

Approximately 1% of all TBEV infections in humans are probably acquired by consuming infected unpasteurised milk or milk products from infected livestock, particularly goats.

Treatment

• There is no specific antiviral treatment available for TBE.
• Because clinical manifestations are non-specific, laboratory confirmation is required for diagnosis of TBE.
• Patients typically need hospitalisation and supportive care based on the severity of signs/symptoms, and usually encompasses maintenance of water and electrolyte balance and administration of:
  • Antipyretics
  • Analgesics
  • Antiemetics
• Anti-convulsive agents, where necessary.
• Patients with neuromuscular paralysis leading to respiratory failure require  intubation and ventilatory support, while those with cerebral edema and who have significantly raised intracranial pressure are often treated with intravenous mannitol and/or steroids.