Serologic Evidence of Exposure to Leishmania infantum in Captive and Free-Ranging European Bison (Bison bonasus) in Poland, 2017-23 .

The European Bison (Bison bonasus) is the largest mammal in Europe and is classified as an endangered species. Leishmaniosis is a vector-borne disease caused by the protozoan Leishmania infantum. In general, this infection has been associated with dogs, cats, and humans. However, epidemiologic studies and reports confirm that the parasite is able to infect many other mammalian species. Recent evidence has demonstrated that ruminants in endemic areas are exposed to L. infantum infection. Moreover, climate change has allowed the northward spread of vector species, causing the expansion of L. infantum infection in regions traditionally classified as nonendemic in Europe. The aim of this study was to determine the presence or absence of anti-L. infantum antibodies in serum samples from 343 European bison in Poland, collected from 2017 to 2023. For this purpose, the presence of anti-Leishmania antibodies was analyzed using an in-house multispecies ELISA. Anti-Leishmania antibodies were detected in four animals, an overall seroprevalence of 1.17%. The results provide scientific evidence of serologic exposure to the parasite in Poland, a country previously considered nonendemic for L. infantum infection.