Sarcocystis infections in bobcats (Lynx rufus) from Minnesota, USA.

Species of Sarcocystis parasitize a wide range of vertebrate hosts, sometimes causing disease in humans and animals. Here, frozen muscles of 239 bobcats (Lynx rufus) from Minnesota were tested for Sarcocystis infections. After thawing, muscles were examined microscopically by compression preparations of unfixed muscles and histological sections of paraffin embedded tissues. Some sarcocysts were later characterized using electron microscopy and gene sequencing for comparison to other Sarcocystis species in the genus. In the first batch of 50 bobcats trapped in 2014-2015, only tongues were examined histologically and sarcocysts were found in 21 (42 %). In the second batch of 140 bobcats trapped in 2023-2024, tongues and limb muscles were examined by combined methods (histology and compression smears) detected infection in the muscles of 44 (31.4 %). In the third batch of 49 bobcats trapped in 2025, tongues, limb muscles and myocardium were examined histologically, and sarcocysts were found in histological sections of 15 tongues, 7 limb muscles and none in hearts. In two of these most heavily infected bobcats, myositis was found in limb muscles. Overall, sarcocysts were detected in 82 of 239 (34.3 %) bobcats. Based on the character of the sarcocyst walls by light microscopy, three morphologic types of sarcocysts were detected. With transmission electron microscopic examination, one of these sarcocyst types could not be distinguished from Sarcocystis felis (originally described from the bobcat) or Sarcocystis caninum (described from the domestic dog) in this study. Multilocus genotyping confirmed one of the Sarcocystis derived from bobcat tongue samples to be either Sarcocystis arctica or Sarcocystis caninum, with all three gene regions (18S rRNA, 28S rRNA, and cox1) showing 98-100 % sequence identity to isolates of S. arctica or S. caninum; S. felis has not been molecularly characterized from the bobcat. Phylogenetic analysis also revealed the clustering of specimens under study with isolates of S. arctica and S. caninum with strong bootstrap support. Results of the study affirm that contrary to assumptions, muscular Sarcocystis infections in bobcats are common, Sarcocystis species may not be host specific in the carnivorous hosts, and some of them cause clinical disease in dogs.