A Different Viewpoint.
he following compendium has been created by experts on TBE,
in collaboration with Baxter.
In several European countries, tick-borne Encephalitis (TBE) is one of the most important human infections of the central nervous system. The disease agent, i.e. the TBE virus (TBEV), is transmitted via tick bites. The virus persists in so-called natural foci, where it circulates among vertebrate hosts (mainly rodents) and the arthropod host (tick).The disease occurs in Western and Central Europe, Scandinavia, countries that made up the former Soviet Union, and Asia, corresponding to the distribution of the ixodid tick reservoir. Most natural foci are well described, but new TBE areas could emerge or re-emerge. At least 10,000 cases of TBE are referred to hospitals each year. TBE has also become an international public health problem because of the increasing mobility of people traveling to risk areas. Today the risk of infection is especially high for all people who pursue leisure activities in nature in endemic areas.
TBE virus is rarely found in Bulgaria, Greece, Italy, Norway, Romania and Japan. Only sporadic cases have been reported so far. In several Euro-pean countries no TBE cases have been found as yet; among these are Great Britain, Ireland, Iceland, Belgium, the Netherlands, Luxemburg, Spain, and Portugal.
Clinical symptoms: The typical clinical picture of TBE is characterized by a biphasic course with non-specific influenza-like symptoms, followed by an asymptomatic interval and a second stage of the disease with at least four clinical manifestations of different severity: meningitis, meningoence-phalitis, meningoencephalomyelitis, meningoradiculoneuritis. Patients may experience just one of the phases. Hospitalization varies between days and months. Up to 46% of patients are left with permanent sequelae and need many years of treatment and rehabilitation measures.1)
Diagnosis: TBE can only be diagnosed accurately by means of laboratory techniques, as the clinical symptoms are not specific for the disease. The virus can be isolated from the blood during the first phase of the disease (PCR). Specific diagnosis usually depends on detection of specific IgM and IgG serum antibodies by ELISA.
Case definition: A confirmed case of TBE is defined as a febrile patient with clinical signs/symptoms of meningitis or meningoencephalitis, mild to moderate elevation of cell counts in CSF, and the presence of serum IgM and/or IgG antibodies against TBE virus.
Therapy: No causal therapy for TBE is known so far.
Prevention: TBE is very easily prevented by vaccination. The Austrian experience gives clear evidence that high vaccination coverage reduces national incidence of TBE effectively.
Lyme borreliosis is another tick-borne disease of similar epidemiologic dimensions in Central Europe. It is caused by spirochetes and can be managed by the administration of antibiotics, whereas no effective therapy exists against TBE. This brochure will mainly deal with TBE.
The clinical picture of TBE was first described in Austria in 1931 by
H. Schneider.2) Shortly afterwards, it was observed in the Far-East of the former USSR, and from 1939 onwards also in its European part. In 1948, the virus was isolated for the first time outside the former USSR.3) In subsequent years, TBE was identified in other European countries. Synonyms for TBE are spring-summer meningoencephalitis, Central European encephalitis, Far-East Russian encephalitis, Taiga encephalitis, or Russian spring-summer encephalitis, biundulating meningoencephalitis, diphasic milk fever, Kumlinge disease, Schneider's disease. The name "tick-borne encephalitis" refers to the tick, its main vector.