This PatientPlus article is written for healthcare professionals so the language may be more technical than the condition leaflets. You may find the abbreviations list helpful.
Tick-borne encephalitis (TBE) is caused by a flavivirus - the same family as yellow fever and japanese encephalitis.
Pathogenesis
- TBE is usually spread by bites from ticks that are infected with the disease. Unpasteurised milk, especially from goats, is also less commonly implicated in spreading the disease.
- The incubation period of TBE is can be from 2 to 28 days (usually between 7 and 14 days) and is asymptomatic. Shorter incubation times have been reported after milk-related exposure.
- Only a small proportion of those infected develop clinical symptoms.[1]
- Symptoms may progress to encephalitis with headache, fever, confusion, agitation and vomiting. Coma may follow.
- Mortality is around 1% for the European form and 5-20% for the Far Eastern version.
The virus subtype has a bearing on the course of the disease. The Eastern variant is more virulent, and leads to severe disease more often than the central one. There is currently little information on the virulence of the Siberian subtype.
Epidemiology
- TBE is endemic across much of Central and Eastern Europe and the incidence is increasing, with numbers estimated to be as many as 8,755 cases per year.[2]
- The Far Eastern type is endemic in areas of China and Japan.
- TBE has never been endemic in the UK.
- Transmission mainly occurs in spring and summer, particularly in rural areas.
Prevention of tick-borne encephalitis
There is no specific treatment for TBE once infected.
- TBE can be prevented by using insect repellents and protective clothing to prevent tick bites.
- Unpasteurised milk should not be drunk in areas at risk:
- Those in tick areas should check their skin for attached ticks, which is easier to do with a partner. However, early removal of ticks does not prevent disease.
- Ticks should be removed as soon as possible with tweezers (or fingers covered by tissue paper if no tweezers are available) as close to the skin attachment as possible, by steady pulling without jerking or twisting.
- Only one to two per cent of ticks are likely to be infected, although up to 10% may be.
- Immunisation should be given if travelling/spending time in endemic or high risk areas.
Tick-borne encephalitis vaccination
There is only one licensed vaccine available in the UK: FSME-IMMUN.
The TBE vaccination is recommended for:
- Those travelling to warm, forested parts of the endemic areas, particularly in the spring and summer, where ticks are most prevalent.
- Individuals who hike, camp, hunt and undertake fieldwork in endemic forested areas.
- Those who will be going to reside in an area where TBE is endemic or epidemic, particularly those working in forestry, woodcutting, farming and the military.
Ideally, immunisation should be completed at least a month before travel. It is considered to be effective against all strains of the disease.
- The first dose is given on day 0.
- The second dose is given one to three months after the first dose.
- The third dose is given five to twelve months after the second dose.
- For rapid short-term protection of children and adults, the second dose may be given two weeks after the first dose and gives at least 90% protection.
- A booster dose should be given every three years if there is continued risk.
- Although the vaccine is not licensed in the UK for use on patients below 36 months of age, it is used routinely in Austria from 18 months of age. Use of the vaccine should be considered in young children if they are going to be at high risk.[3]
- The dose is different for children aged 3-15 years. They should receive half the adult dose.
- Maximum immunity is reached one week after the second dose.
- It can be given at the same time as other inactive vaccines. They should be given at different sites, with different syringes.
- It can be administered at the same time as live vaccines.
Contra-indications
- A confirmed anaphylactic reaction to a previous dose of the TBE vaccine or one of its components.
- A confirmed anaphylactic reaction to egg.
Other information
- Pregnancy or breast-feeding are not contra-indications to this vaccine.
- Local reactions to the vaccine, such as swelling, pain and redness at the site of injection, can occur.
- Some people develop a fever, particularly after the first dose. This is most common within twelve hours of having the vaccine and usually settles within 24-48 hours.
- Following a successful nationwide vaccination campaign in Austria, the annual number of TBE cases fell to about 10% of those reported in the pre-vaccination era.[2]
- The vaccine efficacy rate is around 99%.[4]
Further reading & references
- Health Information for Overseas Travel 'Yellow Book'; Health Information for Overseas Travel 'Yellow Book', National Health Travel Network and Centre (NaTHNAC)
- Tick-borne Encephalitis, Centers for Disease Control and Prevention
- Ruzek D, Dobler G, Donoso Mantke O; Tick-borne encephalitis: pathogenesis and clinical implications. Travel Med Infect Dis. 2010 Jul;8(4):223-32. Epub 2010 Jul 21.
- Kollaritsch H, Chmelik V, Dontsenko I, et al; The current perspective on tick-borne encephalitis awareness and prevention in Vaccine. 2011 Jun 20;29(28):4556-64. Epub 2011 May 5.
- Immunisation - The Green Book; Dept of Health
- Heinz FX, Holzmann H, Essl A, et al; Field effectiveness of vaccination against tick-borne encephalitis. Vaccine. 2007 Oct 23;25(43):7559-67. Epub 2007 Aug 31.
| Original Author: Dr Hayley Willacy | Current Version: Dr Louise Newson | Peer Reviewer: Dr Adrian Bonsall |
| Last Checked: 13/06/2012 | Document ID: 427 Version: 7 | © EMIS |
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
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