Early summer meningoencephalitis (TBE) (synonyms: TBE virus; early summer meningoencephalitis; tick-borne encephalitis; tick-borne encephalitis; ICD-10-GM A84.1: Central European encephalitis, tick-borne) is an infectious disease caused by flaviviruses. The flavivirus family belongs to the list of arboviruses transmissible to humans by arthropods (arthropods). Pathogen reservoir are mainly small animal rodents of the forest and meadows. In rare cases also goats. TBE viruses are mainly transmitted by ticks of the genus Ixodes ricinus (wood tick). In addition, these ticks can transmit Lyme disease.Furthermore, the floodplain tick (Dermacentor reticulatus) can transmit the TBE virus (as of 2017). Occurrence: The previously mentioned infected ticks are vectors of TBE in Europe up to the Ural Mountains as well as in Asia.In Europe, TBE endemic areas are located not only in Germany (see below) but also in Austria, the Baltic countries, southern Sweden, Finland, Russia, Poland, the Czech and Slovak Republics, Hungary, Croatia, Slovenia and Albania. Individual cases are reported from Bornholm (Danish island), France, Italy and Greece.The Russian variant of TBE is called RSSE (Russian Spring Summer Encephalitis).Depending on the region, between 0.1-5% of ticks are infected with the virus. Adult ticks usually stay in vegetation close to the ground at a height of 30-60 cm – in rare cases up to 1.5m. They become active from about 6°-8 °C. Another prerequisite for their activity is a humidity of > 80 %.In contrast to the wood tick, the floodplain tick is active very early in the year and again in autumn until the first snow; thus, the floodplain tick prolongs the period with active and dangerous ticks (prolongation of the active period). Seasonal clustering of the disease: early summer meningoencephalitis occurs in clusters between March and November, with a peak in mid-summer. Note: Due to climate change, ticks are active in Germany almost all year round! Sex ratio: Males contract the disease about twice as often as females. Besides the transmission of the pathogen (infection route) by ticks, transmission via infected milk from sheep, goats or cows is also possible. However, this is very rare. Only about every 100th to 300th tick bite leads to disease, since in endemic areas only an average of 1-3% of ticks are infected with the TBE virus and the clinical manifestation rate is about 33%. However, higher infestation rates of 20-30% are found in individual regions (Lithuania, Russia, Switzerland). Note: Latency between tick bite and infection is usually very short, as TBE viruses reside in the salivary glands of ticks. Incubation period (time from infection to onset of disease) is usually (5) -7-14- (28) days. In TBE risk regions in Germany, up to 2% of ticks are infected. TBE risk areas in Germany include
TBE risk areas in Germany currently include, in particular:
- Baden-Württemberg*
- Bavaria* : (except for some districts [LK] in Swabia and the western part of Upper Bavaria); LK Garmisch-Partenkirchen, LK Landsberg am Lech, LK Kaufbeuren, LK Munich, LK Günzburg, LK Augsburg, LK Weilheim-Schongau and the LK Starnberg.
- Hesse: LK Bergstrasse, city district (SK) Darmstadt, LK Darmstadt-Dieburg, LK Groß-Gerau LK Main-Kinzig-Kreis, LK Marburg-Biedenkopf, LK Odenwaldkreis, SK Offenbach, LK Offenbach.
- Lower Saxony: LK Emsland
- Rhineland-Palatinate: LK Birkenfeld
- Saarland: LK Saar-Pfalz district
- Saxony: SK Dresden, LK Bautzen, LK Erzgebirgskreis, LK Meißen, LK Sächsische Schweiz-Osterzgebirge, LK Vogtlandkreis, LK Zwickau.
- Thuringia: SK Gera, LK Greiz, LK Hildburghausen, LK Ilm-Kreis, SK Jena, LK Saale-Holzland-Kreis, LK Saale-Orla-Kreis, LK Saalfeld-Rudolstadt, LK Schmalkalden-Meiningen, LK Sonneberg, SK Suhl.
* approximately 89% of cases in Germany
RKI – TBE risk areas in Germany.
A TBE risk also exists in other European countries, and especially in Austria and the Czech Republic and as well as throughout Switzerland. Further risk areas exist in Estonia, Finland, Latvia, Lithuania, Poland, Slovakia, Slovenia and Sweden. Sex ratio: Men are affected nearly twice as often as women. Frequency peak: According to the RKI, the risk of contracting the disease increases significantly from the age of 40. Not every infection leads to disease. Approximately every third person bitten by an infected tick becomes ill.In Germany, only about 438 cases were reported in 2011. However, the number of unreported cases is likely to be much higher, as the disease is often misinterpreted as summer flu. Course and prognosis: About 30% of infections are symptomatic. The infection proceeds biphasically (in two phases). In the early phase, only flu-like symptoms occur, whereas in the second phase, which follows a symptom-free interval, neurological symptoms appear. The course is strongly dependent on age: The older the person, the more severe the course of TBE can be, and the more severe the disease, the greater the risk of suffering permanent sequelae of the disease, such as impaired balance or paresis (paralysis) of the extremities.More than 40% of TBE patients require long-term treatment. The meningitic course has the best prognosis. The prognosis worsens greatly if encephalomyelitis (inflammation of the brain and spinal cord) occurs. In general, children who have TBE have a more favorable prognosis than adults. Vaccination: A vaccination against TBE is available. This is also effective against the Russian variant RSSE (Russian Spring Summer Encephalitis). In Germany, direct or indirect detection of the pathogen is reportable under the Infection Protection Act (IfSG) if the evidence indicates acute infection.
