Travel Medicine

Vaccination

Tick-borne Encephalitis

This vector-borne disease, almost restricted to areas of Europe and Asia, is transmitted to humans by the bite of infected ticks or, less commonly, by ingestion of unpasteurised milk from infected animals (mainly goats). There is no person-to-person transmission.

In endemic zones, travellers are at risk when hiking or camping in rural or forested areas, mainly during the summer months. Most cases occur between April and November, with incidence peaks in spring and summer ("spring-summer meningo-encephalitis"), but the  transmission can occur throughout the year.

Main countries with risk of tick-borne encephalitis:

Albania

Austria

China (north, east)

Croatia

Czech Republic

Denmark

Estonia

France (Alsace)

Germany (south)

Hungary

Japan

Latvia

Lithuania

Norway

Poland

Russia (including Siberia)

Slovak Republic

Sweden (central, south)

Switzerland (north)

Ukraine

Travellers who walk and camp in infested areas are at risk and should be vacinated, no matter some degree of protection may be confered by proper footwear and clothing that covers as much skin as possible, and by applyng insect repellents.

Two inactivated vaccines are produced, in adult and paediatric formulations, but may not be available outside endemic countries. The primary vaccination consists of two doses given intramuscularly 4-12 weeks apart, and a third dose 9-12 months after the second dose; boosters are required to maintain immunity and should be given every 3 years. For rapid short-term protection of children and adults, the second dose may be administered 2 weeks after the first dose. The tick-borne encephalitis vaccines can be given at the same time as other travel and routine vaccines.

The paediatric vaccine is not recommended for children under 36 months, and is contraindicated in children younger than eighteen months old. Contraindications to vaccination include: anaphylactic reactions to a previous dose, to a vaccine component (e.g. thiomersal), or true allergy to egg protein. There is no evidence of risk related to pregnancy or breastfeeding.

Fernando Costa Silva, 2005 (last update: 2009)