Potential ecological distribution of Cytauxzoon felis in domestic cats in Oklahoma, Missouri, and Arkansas.

The ecological distribution of Cytauxzoon felis, an often-fatal tick-borne apicomplexan that infects domestic cats, has not been evaluated or identified despite its continued emergence. Infection of C. felis is characterized by lethargy, icterus, fever, anorexia, anemia, and death. The natural vertebrate reservoir of C. felis is the bobcat (Lynx rufus). To determine the possible distribution of C. felis in three states where infection is common (Oklahoma, Missouri, and Arkansas), two separate approaches to ecological niche modeling were implemented. First, a model relating several different climatic layers to geographic locations where cases of C. felis infection were confirmed in domestic cats was developed to predict the possible distribution of the parasite. The second model incorporated occurrences of bobcats with environmental layers and land cover suitable for tick vectors to identify areas of overlap where C. felis transmission was likely. Results of both models indicated a high probability of C. felis from central Oklahoma to south-central Missouri. However, other predicted areas of C. felis occurrence varied between the two modeling approaches. Modeling the vertebrate reservoir and the tick vector predicted a broader possible distribution compared to modeling cases of C. felis infection in domestic cats. Our results suggest that C. felis is likely to extend beyond areas predicted by case modeling due to the presence of both the vector and reservoir.