Abstract
Tick-borne encephalitis (TBE) is an acute inflammation of the nervous system caused
by a virus of the same name. Reservoirs for the TBE viruses are small rodents of the
forest and meadows and rarely also goats, which explains the spatial limitation to
endemic areas ("natural foci"). TBE virus is transmitted mainly by ticks, but occasionally
also by products from non-pasteurized goat's milk. Infections can occur throughout
the year, but most of the diseases present during the high summer months. More than
90% of infections occur during leisure time. However, it is a typical occupational
disease for farmers and foresters. In approximately 70% of the patients, TBE manifests
itself with a two-phase fever course.
After an incubation period of 5–28 days, the patients first develop a general feeling
of illness, headaches and fever (prodromal phase). After a temporary improvement,
a new episode of fever marks the beginning of the second phase of the disease a few
days later. This is manifested in about 50% of the cases as isolated meningitis, in
40% as meningoencephalitis and in 10% as meningoencephalomyelitis. Frequently, there
are quantitative and qualitative disturbances of consciousness and ataxia. The early
onset of swallowing and speech disturbances, paralysis of the facial and throat muscles
as well as the need for assisted ventilation indicates an unfavorable prognosis. In
children and adolescents, TBE is often unspecific with the symptoms of a flu infection
and thus more benign than in adults. With age, not only the course is more serious,
but also the number of residual deficits increases.
The diagnosis is based on history with stays in a risk area, the neurological symptoms
with marked impairment of the general condition, the demonstration of TBE-specific
IgM and IgG antibodies in the blood and a pleocytosis in the CSF. No specific treatment
for TBE is known so far, but TBE can be successfully prevented by active immunization.
Vaccination is recommended for all persons who stay repeatedly in a risk area.
Key words
tick-borne encephalitis - TBE - meningitis - encephalitis - myelitis - vaccine
