Tick-Borne Encephalitis

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TBE (tick-borne encephalitis; FSME) is a viral disease of the central nervous system which is transmitted to man primarily by tick bites. "TBE is a serious case of acute central nervous system disease, which may result in death or long-term neurological sequelae in 35-58% of patients."¹ TBE is endemic to most European countries, The Russian Federation and possibly China. It is the most important arthropod-transmitted viral disease in Europe, and in some countries it represents a major public health problem. Large outbreaks of TBE, sometimes involving thousands of cases, continue to occur in endemic areas.²

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Although many still believe that ticks fall from trees, they actually live in the soil and don't climb much higher than 25 to 100 centimeters onto grasses and bushes in their search for a blood host. Therefore, we generally brush ticks when we pass through grasses or bushes along forest paths, or when we walk on lawns and in the garden.^3,4 TBE is transmitted through the saliva of infected ticks. Nevertheless, a tick does not need to feed for a long time to pass on the infection - a short feed may suffice to transmit the virus. Tick bites often go unnoticed, which may be the main reason why persons cannot remember having been bitten by a tick.

Tick animation 1:

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The typical course of TBE is biphasic in at least two-thirds of patients.⁶ During the two-phase progression, the so-called first phase of the illness occurs after an incubation period of 6 to 14 days; this is when the virus enters the bloodstream. Patients complain about general symptoms, such as temperature increase, headaches, weakness, and fatigue. These symptoms are often indicated as a common cold. After a frequently symptom-free interval between two and eight days, a sudden and significant increase in temperature marks the beginning of the second phase with typical additional symptoms like headache, neck stiffness, delirium, coordination problems and paralysis of the arms and legs.⁷

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Currently no causal treatment is known for TBE. Prevention by special clothing and tick repellents has proven not reliable enough.³ However, TBE can be successfully prevented by active immunization. The TBE vaccines produced by Baxter are inactivated whole virus vaccines containing a suspension of purified TBE virus, propagated in chick-embryo fibroblast cells of specific pathogen-free eggs, and subsequently subjected to inactivation. TBE vaccine has been approved in Austria since 1976 and has been widely used for many years in 25 European countries, Russia and Canada. Residents of and travelers to TBE endemic areas, who are at risk of tick bites, are advised to receive TBE vaccination.^8,9

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^{1. WHO, State of the Art of New Vaccines: Research & Development 2003. http://www.who.int/vaccine-research /diseases/vector/en/index2.htm}

^{2. WHO; http://www.who.int/biologicals/areas/vaccines/tick_encephalitis/en/}

^{3. Sünder U., Zu Vorkommen und Verbreitung von Borrelia burgdorferi in ausgewählten Naturherdgebieten Thüringens unter besonderer Berücksichtigung der Rolle des Hauptvektors Ixodes ricinus (L. 1758) (2003)}

^{4. Kunz C.; Tick-Borne encephalitis in Europe. Acta Leiden. 1992; 60: 1-14}

^{5. Hofmann H.; Die unspezifische Abwehr bei neurostropen Arbovirusinfektionen. Zbl. Bakt. Hyg. 1973; 223 (I. Abt. Orig. A): 143-163}

^{6. Kaiser R.; Tick-borne encephalitis (TBE) in Germany and clinical course of the disease. Int J Med Microbiol. 2002 Jun; 291 Suppl 33: 58-61}

^{7. Adapted from Radda A. C.; Die Frühsommer-Meningoenzephalitis in Österreich; Dr.Med. 1980; 4:4-8}

^{8. Kunze U.: The Golden Agers and Tick-Borne encephalitis WMW (2005); 155/11-12}

^{9. Barrett PN, Schober-Bendixen S., Ehrlich HJ., History of TBE vaccines. Vaccine 21 (2003) S1/41-S1/49}

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