Citation: Larska, M.; Tomana, J.; Socha, W.; Rola, J.; Kubi´ s, P.; Olech, W.; Krzysiak, M.K. Learn the Past and Present to Teach the Future—Role of Active Surveillance of Exposure to Endemic and Emerging Viruses in the Approach of European Bison Health Protection. Diversity 2023, 15, 535. https://doi.org/10.3390/d15040535 Academic Editor: Olivier A. E. Sparagano Received: 8 February 2023 Revised: 31 March 2023 Accepted: 2 April 2023 Published: 7 April 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). diversity Article Learn the Past and Present to Teach the Future—Role of Active Surveillance of Exposure to Endemic and Emerging Viruses in the Approach of European Bison Health Protection Magdalena Larska 1, * , Jaroslaw Tomana 2 , Wojciech Socha 1 , Jerzy Rola 1 , Piotr Kubi´ s 3 , Wanda Olech 4 and Michal K. Krzysiak 5,6 1 Department of Virology, National Veterinary Research Institute (NVRI), Partyzantów 57, 24-100 Pulawy, Poland 2 Veterinary Clinic, ul. Kili´ nskiego 3A, 43-200 Pszczyna, Poland 3 Department of Biochemistry, National Veterinary Research Institute (NVRI), Partyzantów 57, 24-100 Pulawy, Poland 4 Department of Animal Genetic and Conservation, Institute of Animal Sciences, Warsaw University of Life Sciences SGGW, Ciszewskiego 8, 02-786 Warszawa, Poland 5 Bialowie ˙ za National Park, Park Palacowy 11, 17-230 Bialowie ˙ za, Poland 6 Institute of Forest Sciences, Faculty of Civil Engineering and Environmental Sciences, Bialystok University of Technology, Wiejska 45 E, 15-351 Bialystok, Poland * Correspondence: m.larska@piwet.pulawy.pl; Tel.: +48-818-893-068 Abstract: As the population size of free-living European bison in Poland has increased significantly over the last few years, conservation and management should be reconsidered to face new challenges, which aim to protect the whole population, not just individuals. The aim of our study was to analyse prevalence and identify risk factors for infections with viruses affecting reproduction (BVDV, BoHV-1, and BoHV-4), causing respiratory diseases (BRV3, BAdV-3, and BRSV), and emerging vector-borne viruses (BTV and SBV). Over 600 serum samples used in serology and 270 lung tissue samples, and 284 nasal swabs used in virological tests were collected from 24 free-living and captive European bison herds between 2016 and 2023. The seroprevalences varied between low (0.3–6.1% for BVDV, BoHV-1, and BoHV-4), medium (15.9% for BRSV and 22.1% for BTV) and high (43.3% for BRV3, 59.5% for BAdV-3, and 69.5% for SBV). Interspecies’ and intraspecies’ risk of endemic viral infections was observed to be density-dependent, while the effect of anthropogenic factors on the spread of infections in free-living European bison has not been demonstrated. BTV is no longer circulating, while SBV has become endemic. The higher exposure to viruses in the European bison eliminated on the basis of a veterinary decision indicates the importance of an expert supervision for disease control and prevention. Keywords: European bison; surveillance; infection ecology 1. Introduction The European bison (Bison bonasus) is the largest land mammal in Europe, which was rescued from total extinction in the wild just after the First World War. This year, the anniversary of 100 years of restitution will be celebrated to commemorate the undertaking to start the recovery of the species from the remaining specimens scattered in enclosures throughout Europe. In addition to the limited gene pool (the species has been recovered only from 12 individuals, including only seven as founders of the Lowland line—LB), the main threats to the species involve epidemiological threats. As the Polish population has reached close to 2500 individuals, which is over one fourth of the Bison bonasus world population [1] and its status has changed to ‘Near Threatened’ on the IUCN Red List [2], conservation and management should be reconsidered to face new challenges, which aim Diversity 2023, 15, 535. https://doi.org/10.3390/d15040535 https://www.mdpi.com/journal/diversity