Early summer meningoencephalitis A84.0

Meningitis or meningoencephalitis caused by arboviruses (TBE virus) transmitted by a tick bite (see also ticks).

Early summer meningoencephalitis (TBE) is caused by a virus of the genus Flavivirus ( Flaviviridae ) in the Flaviviridae family, to which other human pathogenic viruses such as dengue, yellow fever, West Nile virus, etc. belong. In Germany, the Central European subtype occurs, which is mainly transmitted by the tick Ixodes ricinus. In addition, there is also a Far Eastern and a Siberian subtype, which occur in Europe in the Baltic region and on the Finnish coast as well as in Asia, where they are transmitted by the tick I. persulcatus.

Important endemic areas in Germany are located in Baden-Württemberg, Bavaria and in southern Hesse and Thuringia. In addition, individual districts in Rhineland-Palatinate (Birkenfeld district), Saarland (Saar-Palatinate district) and Saxony (Vogtland district) are also affected. In German endemic areas about 0.1% of ticks are virus carriers.

After inoculation into the skin, the virus initially multiplies locally, reaching the regional lymph nodes via the draining lymphatic vessels. From here it enters the thoracic duct via efferent lymph channels and thus into the bloodstream.

In the subsequent viremia, the virus colonises extraneural organs such as connective, muscle and glandular tissue.

After a further replication phase, the virus infects the central nervous system by haematogenic means.

Depending on the activity of the virus-carrying ticks, TBE occurs preferentially in spring and summer, but often also in autumn. In warm weather, infections can occasionally occur in winter as well.

The transmission is by tick bite, very rarely by virus-infected raw milk from goats and sheep, in exceptional cases also from cows. There is no infection from person to person. The incubation period is 5-20 days.

In 60-70% of infected persons the disease progresses subclinically. 15-30% have only unspecific flu symptoms. 10-20% develop neurological symptoms (meningitis 55%, meningo-encephalitis 5%), residual symptoms in 7%, lethality 1%.

Previous exposure in a risk area, observed tick bite within the last 3 weeks, inflammatory CSF syndrome (initially predominantly granulocytic, later lymphocytic pleocytosis, mild blood CSF barrier disorder, facultative intrathecal IgM and low IgG and IgA synthesis).

Positive detection of TBE specific IgM and IgG antibodies in serum; intrathecal synthesis of TBE specific antibodies > 90% of cases.

Active immunisation with TBE inactivated virus (e.g. TBE immune).

Basic immunisation: 3 times at intervals of 2 weeks and one year 0.5 ml suspension i.m. (immunity for 3 years).

Post-exposure: Passive immunisation (TBE immunoglobulins i.m.) in the first 48h 0.1ml/kg bw TBE-Bulin®, afterwards 0.2ml/kg bw after tick bite (not later than 96 h after the bite) in the endemic areas in unvaccinated persons.

Note: The benefit is neither proven nor excluded.

In terms of Europe, major TBE endemic areas are located in central Europe in Austria, Poland, the Czech Republic and Slovakia, in northern Europe in the Baltic countries, south, central Sweden, on the southern coasts of Norway and Finland and in parts of Denmark (sporadically on Zealand, endemic on the island of Bornholm) and in the European part of Russia as well as in south-eastern Europe in Hungary, Croatia, Slovenia and Albania (Communication from the RKI - www.rki.de/jahrbuch). Of lesser importance are France (Alsace), Italy (Trentino) and Greece (individual cases). There is no TBE risk in the Iberian Peninsula, the United Kingdom and the Benelux countries.

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