5 July 2012
Risk of tick-borne disease: advice for travellers to Europe
There are native tick species in Europe, such as Ixodes and Hyalomma, capable of transmitting disease [1, 2]. Ticks are found in woods and grasslands all across Europe from early spring to late autumn . Ticks infected with a virus or bacterium, transmit the infection to humans through bites . Travellers can be at risk of these tick-borne diseases.
Tick-borne encephalitis (TBE)
European TBE is transmitted by Ixodes ricinus ticks present in forest and mountainous areas in western and central Europe. TBE is endemic in Austria, Belarus, Croatia, the Czech Republic Estonia, Germany, Hungary, Latvia, Lithuania, Poland, western Russia, Slovakia, Slovenia Switzerland and Ukraine. It is also reported in the Åland archipelago, neighbouring Finnish coastline, Denmark, France, Italy, Kazakhstan, Liechtenstein, Norway, Romania and Sweden. Albania, Bosnia, Bulgaria, Greece, Herzegovina, Moldova, Montenegro and Serbia also report cases, but the incidence of disease is unknown. TBE does not occur in the UK, but very occasionally (less than one per year) cases may be imported by UK travellers who have been to endemic areas.
The majority of infected individuals do not have any symptoms, with the ratio of asymptomatic to symptomatic infection approximately 250 to 1. Most people with symptoms recover. However, up to a third can suffer long-term complications due to the encephalitis. Treatment of those infected with TBE is supportive only [1, 4]. There is an effective vaccine available .
Lyme disease is caused by a bacterium, the spirochete Borrelia burgdorferi. It is transmitted to humans by bites from infected Ixodes ticks. The highest reported incidence of Lyme disease is in central Europe, with the highest tick infection rates in the forested woodlands of Austria, Czech Republic, southern Germany, Switzerland, Slovakia and Slovenia . In 2011, 972 cases of Lyme borreliosis were reported in England and Wales: 17% of these had been abroad to North America and Europe  Symptoms include a characteristic skin rash called ‘erythema migrans’, fever, malaise, and myalgias. Some patients can have neurological symptoms. Lyme disease is treated with antibiotics [6, 7]. There is no vaccine currently available.
Crimean Congo Haemorrhagic Fever (CCHF)
CCHF is a viral infection transmitted by Hyalomma ticks. It occurs in Eastern Europe and the Mediterranean. European outbreaks have also been reported in Albania, Greece, Kazakhstan, Kosovo and Turkey . CCHF is rare in travellers. However, in 1997, CCHF was reported in a UK traveller who had been to Zimbabwe .
Symptoms are often mild starting one to three days after a tick bite. Symptoms include fever, dizziness, headache, myalgia and photophobia [8, 9]. This can progress to hemorrhagic manifestations and death. The case fatality rate is between 20% and 35% .Treatment is supportive. There is no vaccine currently available.
Advice for travellers
Advice for health professionals – the returned traveller
Health professionals should be alert to the possibility of a tick-borne disease in ill-returned travellers from Europe or neighbouring countries [7, 10].
1. Tick-borne Encephalitis. Ch. 5 – Disease Guide. In: Field VF, Ford L, Hill DR (Eds). Health Information for Overseas Travel. National Travel Health Network and Centre. London, UK. 2010
2. European Centre for Disease Prevention and Control. Tick-borne diseases. May 2012. [Accessed 5 July 2012]. Available at: http://ecdc.europa.eu/en/healthtopics/tick_borne_diseases
3. European Centre for Disease Prevention and Control. VBORNET maps: Tick species – Distribution Maps. March 2011. [Accessed 5 July 2012]. Available at: http://www.ecdc.europa.eu/en/activities/diseaseprogrammes/
4. European Centre for Disease Prevention and Control. Key Message 1: Ticks can carry disease. May 2012. [Accessed 5 July 2012]. Available at: http://ecdc.europa.eu/en/healthtopics/tick_borne_diseases/key
5. Eurosurveillance 16 (27) 2011. Lyme borreliosis in Europe. Rizzoli A, Hauffe HC, Carpi G, et al. [Accessed 5 July 2012]. Available at: http://www.eurosurveillance.org/images/dynamic/EE/V16N27/
6. Health Protection Agency: Epidemiology of Lyme borreliosis in England and Wales 2011. 4 May 2012. [Accessed 5 July 2012]. Available at: http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPA
7. Health Protection Agency: Diagnosis and Treatment of Lyme borreliosis. 29 May 2012. [Accessed 5 July 2012]. Available at: http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/
8. Health Protection Agency: Crimean-Congo Haemorrhagic Fever – Background Information. 20 April 2012. [Accessed 5 July 2012]. Available at: http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ
9. Crimean-Congo Haemorrhagic Fever. Ch. 5 – Disease Guide. In: Field VF, Ford L, Hill DR (Eds). Health Information for Overseas Travel. National Travel Health Network and Centre. London, UK. 2010.
10. The Ill Returned Traveller Ch. 4.2 In: Field VF, Ford L, Hill DR (Eds). Health Information for Overseas Travel. National Travel Health Network and Centre. London, UK. 2010.