Babesia odocoilei infection in a North American elk (Cervus elaphus canadensis)

Abstract

A 13-year-old, male, North American elk (Cervus elaphus canadensis) from a commercial herd was presented for a sudden onset of lethargy, anorexia, and hematuria to Palmer Veterinary Clinic, Plattsburgh, NY, USA. The elk, originated from Ohio, was from a herd of 60 animals with an age range of 2 months to 13 years. Clinically, over a 5-7-day period, the elk began to distance itself from the remainder of the herd, and became anorectic and eventually recumbent. Results of the admitting complete blood count indicated a normocytic, normochromic, nonregenerative anemia. The animal was serologically negative for elk wasting disease. Supportive treatment did not result in clinical improvement. The elk was euthanized because of the rapidly declining condition. At necropsy, the spleen was diffusely enlarged and the mesenteric and periaortic fats were yellow. Microscopically, the only finding of note was extensive splenic erythrophagocytosis. Microscopic examination of a peripheral blood film stained with Wright-Giemsa revealed that about 5% of erythrocytes contained protozoal parasites. The morphologic characteristics of these organisms were consistent with Babesia organism, most likely Babesia odocoilei. Using a nested polymerase chain reaction, the organism was identified as B. odocoilei. To the authors' knowledge, this is the first report of B. odocoilei infection in North American elk in New York State, USA. We recommend that infection with B. odocoilei be considered in any case of acute hemolytic anemia in elk.A 13-year-old, male, North American elk (Cervus elaphus canadensis) from a commercial herd was presented for a sudden onset of lethargy and hematuria to Palmer Veterinary Clinic, Plattsburgh, NY, USA. The elk, originated from Ohio, was from a herd of 60 elks with an age range of 2 months to 13 years. Clinically, over a 5-7-day period, the elk began to distance itself from the remainder of the herd, and became anorectic and eventually recumbent. Results of the admitting complete blood count indicated a normocytic, normochromic, nonregenerative anemia (hematocrit 29%, reference interval 37-55%). The serum clinical chemistry data revealed hypoalbuminemia (2.1 g/dL, reference interval 2.5-3.5 g/dL), hypocalcemia (7.1 mg/dL, reference interval 8.0-12.0 mg/dL), hypophosphatemia (2.7 mg/dL, reference interval 4.0-8.6 mg/dL), hyperbilirubinemia (4.5 mg/dL, reference interval 0.0-0.7 mg/dL), and increased urea nitrogen (BUN) concentration (45 mg/dL, reference interval 10-25 mg/dL). The animal was serologically negative for elk wasting disease. Supportive treatment (fluids, electrolytes, and antibiotics) did not result in clinical improvement, and the elk was euthanized because of the rapidly declining condition.

Prevalence of Winter Ticks (Dermacentor albipictus) in Hunter-Harvested Wild Elk (Cervus canadensis) from Pennsylvania, USA (2017–2018)

“…Common pathogens transmitted by winter ticks include Anaplasma marginale and Babesia duncani [ 4 , 5 ]. Although there have been no recorded cases of B. duncani infection in elk, Babesia odocoilei can cause severe Babesiosis characterized by hematuria, lethargy, and death [ 6 ]. Additionally, elk have been shown to develop asymptomatic infections after experimental infections with A. marginale [ 7 ].…”

Babesia odocoilei infection in a Saskatchewan elk (Cervus elaphus canadensis) herd

“…To date, North American elk have only been reported to be infected with B. odocoilei; however, PCR is required to confirm the species involved, as well as to differentiate from other morphologically similar organisms such as Theileria spp. Polymerase chain reaction analysis has typically been performed on peripheral blood 1,4,7,9,11,20 ; in the present case, both fresh frozen spleen and velvet antler were also successfully used to amplify Babesia 18S rRNA. The option to use these tissues is advantageous in situations where peripheral blood has not been collected and only banked tissues are available for diagnostic testing.…”

“…12 In the current case, the elk cow had severe anemia, at a level that seemed inconsistent with the clinical description of the animal. Hematocrit has been reported to range from 28.8% to 33.7% in clinically affected elk, 1,7 and as low as 11% in a clinically affected reindeer, 4 values that are significantly higher than the 3.9% hematocrit in the elk cow. Although blood from this animal was not collected by venipuncture, there was no evidence of sample contamination by lymph or other body fluids during collection, and the EDTA tube was filled with an appropriate volume of blood, making dilution by the anticoagulant unlikely.…”

“…4 Naturally acquired infections of B. odocoilei was first reported in Texas 6 and have also been reported in numerous locations in the United States, primarily the north-central and the northeastern regions. 1,4,7,9,19,20 To the authors’ knowledge, there have been no prior reports in Canada.…”

“…Reticulocytosis has not been described in previous reports of babesiosis in elk, even when the hematocrit was moderately decreased. 1,7 As a result, the ability of elk to mount reticulocytosis in response to anemia has been questioned. 7 In the current case, reticulocytosis was present, accompanied by abundant basophilic stippling, typical of a ruminant regenerative response.…”