Seroprevalence of tick-borne encephalitis (TBE) in naturally exposed monkeys (Macaca sylvanus) and sheep and prevalence of TBE virus in ticks in a TBE endemic area in Germany.

In a recently published study, a clinical case of severe tick-borne encephalitis (TBE) in a monkey (Macaca sylvanus) was described after natural exposure (tick bite) in a TBE endemic area in Germany, and from the tissue of this monkey the strain 'Salem', closely related to the strain 'Neudoerfl', was isolated and characterized. In this study, it was our aim to test all the available data for characterizing a TBE endemic area like TBE cases in humans and animals, TBE virus (TBEV) in ticks, and TBE-positive sera from animals. Sera from 283 monkeys and 100 sheep as well as 294 unfed ticks were collected at the monkey mountain Salem and its surroundings. A seroprevalence of 2.6% in monkeys and 9% in sheep were found. Furthermore, a new real-time RT-PCR method was established and used, in combination with an already published RT-qPCR, for TBEV genome detection in field-collected ticks, but no TBEV could be detected in the ticks tested.

Klaus C ，Hoffmann B ，Beer M ，Müller W ，Stark B ，Bader W ，Stiasny K ，Heinz FX ，Süss J ... -  《-》

Isolation and molecular characterization of a tick-borne encephalitis virus strain from a new tick-borne encephalitis focus with severe cases in Bavaria, Germany.

Tick-borne encephalitis (TBE) is the most important viral infection transmitted by ticks in Central Europe. In Germany, where TBE was classified as a notifiable disease in 2001, a highly variable number of clinically apparent human cases was reported in the last few years, ranging from the lowest number of 238 in 2007 to a maximum of 546 in 2006. The dynamics of the virus and its vector tick remain poorly understood. We investigated a highly active TBE focus in south-eastern Germany where from 2003 to 2008 a total of 9 clinical human cases was diagnosed. Three out of these 9 cases were fatal indicating an unusually high mortality rate possibly due to a highly virulent TBEV strain. From 2005 till 2008, 2150 Ixodes ricinus ticks were collected and tested for the presence of TBE virus. Five TBEV-positive ticks were detected by real-time RT-PCR. A viable virus strain was isolated from one of the positive ticks sampled in 2005. This is the first TBE virus isolate from a tick in Germany for 30 years. Sequencing of the full-length genome of this virus strain (AS33) revealed 2 unique amino acid substitutions in the envelope protein known to play a role in the pathogenicity of TBE virus. Amplification of the envelope gene using 2 TBEV-PCR-positive ticks from 2006 also showed these particular mutations indicating that this TBE virus strain was present in at least 2 consecutive years. The entire sampling area was divided into smaller sectors for the exact location of TBEV-positive ticks. Virus-positive ticks were found to be randomly distributed throughout the investigated focus, which is used as recreational area by the local people.

Kupča AM ，Essbauer S ，Zoeller G ，de Mendonça PG ，Brey R ，Rinder M ，Pfister K ，Spiegel M ，Doerrbecker B ，Pfeffer M ，Dobler G ... -  《-》

Goats and sheep as sentinels for tick-borne encephalitis (TBE) virus--epidemiological studies in areas endemic and non-endemic for TBE virus in Germany.

The aim of the study was to examine grazing goats and sheep as specific sentinels for characterization of the tick-borne encephalitis virus (TBEV)-related risk in an area by means of serosurveillance tests in the German federal states Baden-Wuerttemberg, Bavaria, Thuringia, North Rhine-Westphalia, Lower Saxony, Schleswig-Holstein, and Mecklenburg-West Pomerania. A total of 3590 sheep sera and 3793 goat sera was collected in 2003 and 2006-2009 and were examined by ELISA screening and confirmed by serum neutralization test. Considerable differences in seroprevalence were seen between single flocks in districts in Baden-Wuerttemberg, Bavaria, and Thuringia with values between 0 and 43% which confirmed the patchy pattern of TBEV foci that can range in size from very small to large. The here described serological screening may be a helpful tool for an early warning system of a potential TBEV risk. Testing of 1700 ticks by real-time RT-PCR in two districts in Baden-Wuerttemberg revealed only one positive tick, thus illustrating the problems of expensive and time-consuming tick collection.

Klaus C ，Beer M ，Saier R ，Schau U ，Moog U ，Hoffmann B ，Diller R ，Süss J ... -  《-》

Tickborne encephalitis in naturally exposed monkey (Macaca sylvanus).

Süss J ，Gelpi E ，Klaus C ，Bagon A ，Liebler-Tenorio EM ，Budka H ，Stark B ，Müller W ，Hotzel H ... -  《-》

[Tick-borne encephalitis virus in humans and ticks in Northeastern Germany].

Tick-borne encephalitis (TBE) was known to have occurred in humans in the area of Mecklenburg-Western Pomerania in Germany, until 1985. Between 1992 and 2004 more than 16,000 ticks were tested and found to be negative for TBE virus in that area of Germany, wich was therefore thought to be free of TBE. But after 19 years three autochthonous cases of human TBE-infections were identified between 2004 and 2006. We subsequently collected ticks from the three areas where the infection had been acquired and tested them for the presence of TBE-virus RNA with a nested reverse transcription polymerase chain reaction (RT-PCR). Since there is evidence that a blood-meal leads to an increase of FSME-RNA in ticks, we tested both, unfed ticks and ticks after a blood-meal. Three unfed and one fed nymph from the area around Lake Woblitz and one unfed and one fed nymph from Thiessow were positive for TBE-virus RNA. A total of six of 250 (2.4%) ticks tested positive for TBE-virus. The emerging of human TBE infections in three regions in Mecklenburg-Western Pomerania shows that the activity of natural TBE virus foci does not cease even after decades, or that TBE-infected ticks could have recolonized these regions.

Frimmel S ，Krienke A ，Riebold D ，Löbermann M ，Littmann M ，Fiedler K ，Klaus C ，Süss J ，Reisinger EC ... -  《-》