Infection with the Neorickettsial Organism Stellantchasmus falcatus Agent in an Arctic Fox (Vulpes lagopus).

A 1-year-old female-intact arctic fox (Vulpes lagopus) presented for diarrhea, lethargy, severe thrombocytopenia, and hyperbilirubinemia. Blood film evaluation revealed intracytoplasmic coccoid bacteria within moderate numbers of leukocytes consistent with infection by a rickettsial organism. Similar organisms were observed within many leukocytes from fine-needle aspirates of an enlarged peripheral lymph node. The lymph node also contained moderate necrosis and an expansion of granular lymphocytes. Parasitic ovum consistent with the trematode Nanophyetus salmincola was found on fecal floatation. The patient responded to treatment with doxycycline, enrofloxacin, ampicillin/sulbactam, and other supportive therapies. Polymerase chain reaction testing confirmed the presence of Neorickettsia sp., and DNA sequencing identified the organism as Stellantchasmus falcatus agent. To the authors' knowledge, this is the first report describing this organism microscopically in peripheral blood, the first reported case of infection in this species of canid, and describes the various clinicopathologic changes with this infection.