Chronic Cytauxzoon felis infections in wild-caught bobcats (Lynx rufus)

Cytauxzoon felis, and the resulting disease, cytauxzoonosis, is an emerging threat to domestic cats in the Midwest and Southeastern United States. Domestic cats that survive cytauxzoonosis (or are subclinically infected) are chronically infected with C. felis, yet to date, there is no information relative to chronic infections in bobcats, the natural reservoir. Over a period of 3.5 years (2014-2017), we captured and re-captured 5 bobcats in southern Illinois. One bobcat was captured each year of trapping, 1 was caught in the first and third year and 3 were recaptured approximately 1 year apart. We screened bobcats for the presence of C. felis using a nested PCR that amplified the nuclear small subunit (SSU) 18S rRNA. In addition, we amplified and sequenced the internal transcribed spacers 1 and 2 (ITS1 and ITS2) to detect if the strains of C. felis in each bobcat were consistent over time. All bobcats were positive for C. felis at the initial and subsequent capture(s). Bobcats that were PCR-positive for C. felis had blood smears screened for the presence of C. felis; all PCR-positive bobcats had detectable parasites in blood smears. The strains of C. felis present were consistent each year in 4 of 5 bobcats indicating these bobcats remained infected during this period. One bobcat appeared to be infected with a different strain based on a polymorphism at a nucleotide in ITS1. Our study provides important details of the epizootiology of C. felis: bobcats are chronically infected and are not immune to reinfection with new strains of C. felis.