Tick-borne encephalitis is an inflammatory disease of the brain or brain membranes, which is triggered by the TBE virus. This pathogen is transmitted by ticks. The infection of the ticks with the TBE virus is very different from region to region - and thus the respective risk of infection. Immunization by vaccination can reduce the risk of TBE.In some regions, the TBE virus is endemic, which means that it is spread all over Austria. Other endemic areas are in Germany, the Czech Republic, Slovakia, Slovenia, Poland, Russia and the Baltic States. In these areas the disease occurs - especially from March to November, with a peak from July to September.
Experts estimate that three-quarters of TBE infections do not show symptoms. In the remaining cases, a characteristic two-phase course may occur. However, one of the two stadia may also be missing.
The incubation period - ie, the time between tick bite and outbreak of disease - is one week to about three weeks. Then there is a fever with flu-like symptoms such as headache and muscle pain, general exhaustion, respiratory problems, stomach pain or diarrhea. In approximately two-thirds of patients with symptomatic course, the disease ends with the fall in fever at this stage.
However, the remaining patients develop neurological symptoms - usually after a fever-free period of six to ten days. In individual cases, however, the first stage also transitions directly into a second phase of disease.
In phases two, it comes to:
These disorders can manifest themselves in severe headaches, neck stiffness, confusion and disturbances of consciousness. It can also lead to gait disturbances, seizures, paralysis and breathing problems. Much of the patients recover fully, with ten to 29 percent of patients with meningoencephalitis or meningoencephalomyelitis having paralysis, hearing loss, reduced performance, depressive moods, or other impairments over long periods. In children the disease is generally less severe.
Only about half of those affected noticed that they were stung by a tick. Therefore, a safe diagnosis is therefore possible only with the help of labordiagnosis. This serves, above all, to differentiate against other infectious diseases with similar symptoms.
The method of choice to ensure diagnosis is the detection of TBE-specific IgM and IgG antibodies (immunoglobulins) in the patient's serum, which are always present at the onset of neurological symptoms.
Since there is no special treatment for TBE, it is advisable to vaccinate persons who live in risk areas. This also applies to people who travel to such areas.
Immunization against early summer meningoencephalitis consists of three partial vaccinations. A vaccine containing inactivated viruses is injected into the muscles of the upper arm (Musculus deltoideus). After complete basic immunization, 99% of the vaccinees have complete protection against TBE. Even only two vaccinations at the regular distance protect 90 per cent, for about one year. The TBE vaccines available in Austria are equivalent to the recommendations of the National Vaccine Committee in the Ministry of Health and provide protection against all known subtypes of the TBE virus.