First Detection of Bluetongue Virus Type 3 in Poland, 2024—A Case Study in European Bison (<i>Bison bonasus</i>)

The emergence of an another bluetongue virus serotype BTV-3 has been causing great losses in animal farming in Europe since fall 2023. The virus spreads faster than the epidemic BTV-8, which appeared on the continent nine years earlier. The study describes first case of BTV-3 in Poland detected in European bison (Bison bonasus), just approx. 15 km from the German-Polish border. The animal suffered from severe and fatal hemorrhagic disease. The symptoms included respiratory problems, bloody diarrhea and rapidly progressive cachexia. In addition to confirmation of BTV-3 infection in the blood and spleen of the animal, the virus was also detected in one of pool of blood-fed Culicoides punctatus caught near the enclosure two weeks after the death of European bison. This is the first evidence of BTV-3 detection in C. punctatus what suggests vector competency for this serotype. Phylogenetic analysis based on the segment 2 of the virus revealed homology of Polish isolate to the BTV-3 strains circulating in the Netherlands, Germany and Portugal, and slightly lower similarity the BTV-3 strains detected in sheep in Sardinia (Italy) in 2018 and in Tunisia in November 2016. Retrospective serosurvey of the exposure to BTV in thirteen other European bison populations widespread in the country indicated that the observed case at the Wolin National Park was the first BTV-3 to be detected in Poland.