Incidence of tick-borne encephalitis virus (TBEV) in horses from Germany (2010–2020)

Background Tick-borne encephalitis virus (TBEV) is a member of the genus Flavivirus within the family Flaviviridae. The virus is spread over a wide area of the Eurasian continent. In Germany it is mainly transmitted by Ixodes ricinus. Main objective of this retrospective study was to assess the incidence of TBEV in horses in Germany.

Methods This study included test results of direct (PCR) and indirect detection methods (IgG-all species-ELISA) for TBEV from horses requested by German veterinarians from January 2010 to December 2020. Additionally, an IgM-ELISA was available from June 2019 onwards. The samples were analyzed by LABOKLIN (Bad Kissingen, Germany).

Results 203 horses were included in the study. Fifty-nine out of 178 horses (33%) were tested serologically positive for IgM- (12/124, 10%) and/or IgG-antibodies (51/174, 29%). Taking federal states with at least 10 tested horses in consideration, the highest amount tested positive was in Bavaria (16/28, 57%), Berlin-Brandenburg (16/43, 37%), Hesse (3/10, 30%) and Lower Saxony (9/33, 27%). All 28 PCR-tests were negative.

Discussion and Conclusion Fifty-nine out of 178 horses (33%) were tested serologically positive for TBEV. The monthly distribution of positive test results of IgM-antibodies correlates well with the highest activity of Ixodes ricinus-ticks. Cross-reactions with other Flaviviridae, esp. West Nile Virus, have to be taken into consideration. The highest incidences were found in horses from southern federal states as well as Berlin-Brandenburg and Lower Saxony. Whereas Bavaria as well as parts of Hesse and Lower Saxony are considered as high-risk areas in human medicine in Germany, Berlin-Brandenburg so far is not.

Publication History

Article published online:
06 May 2022