Original Title: Hepatozoon spp. infection in wild canids in the
eastern United States

Abstract
Background: Hepatozoon spp. are apicomplexan parasites known to cause musculoskeletal disease in a variety of animals. Two species are known to infect wild and domestic canids in the United States: H. canis and H. americanum.

Methods: In this study, blood, heart, and/or spleen samples were collected from 278 wild canids (180 coyotes, 93 red foxes, and 5 gray foxes) in the eastern United States and tested via PCR for Hepatozoon. Necropsies were performed when whole carcasses were available (n=94), and histology slides of heart and skeletal muscle were assessed for Hepatozoon cysts and associated inflammation.

Results: Hepatozoon spp. were found in 24.2% (59/278) of individuals, with H. canis in 14.0% (34/278) and H. americanum in 10.7% (26/278). One coyote was positive for both H. canis and H. americanum. Foxes were more likely to be positive for H. canis than coyotes (23% and 7% respectively, p=0.0008), while only coyotes were positive for H. americanum. Of the eight sampled states, H. canis was present in six while H. americanum was found in two southern states (South Carolina and Louisiana). Infection status was positively correlated with myositis and myocarditis, and heart or muscle cysts were found in 83% (5/6) of H. americanum positive coyotes.

Conclusion: This survey showed a moderate prevalence of Hepatozoon spp. in states where the parasite was previously unrecorded including Tennessee, South Carolina, and Pennsylvania.

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