Milnes Ellie L, Thornton Grace L, Delnatte Pauline, Léveillé Alexandre N, Barta John R, Smith Dale A, Nemeth Nicole M
1 Ontario Veterinary College, University of Guelph, 50 Stone Rd. E., Guelph, Ontario N1G 2W1, Canada.
2 Toronto Zoo, 361A Old Finch Ave., Toronto, Ontario M1B 5K7, Canada.
J Wildl Dis. 2019 Apr;55(2):335-342. doi: 10.7589/2018-06-147. Epub 2018 Oct 19.
Babesia odocoilei, a tick-borne protozoan hemoparasite of white-tailed deer ( Odocoileus virginianus), is being increasingly recognized as a cause of disease in captive cervids in North America. Historically endemic in white-tailed deer, the natural wildlife reservoir in the southeastern US, B. odocoilei has been recently associated with hemolytic anemia in captive Eurasian tundra reindeer ( Rangifer tarandus tarandus), wapiti ( Cervus canadensis), and woodland caribou ( Rangifer tarandus caribou) in the northcentral and northeastern US and several Canadian provinces. The emergence of B. odocoilei is likely related to the northward expansion of the range of the tick vector, Ixodes scapularis, and possibly to cervid translocations. Following a disease outbreak in reindeer and wapiti at the Toronto Zoo in Ontario, Canada, we utilized a prospective postmortem survey to investigate the prevalence of B. odocoilei in wild, farmed, and zoo cervids in Ontario ( n=270) in 2016-18 by PCR and DNA sequencing of spleen samples. Zoo bovids have been suggested as potential hosts of B. odocoilei in zoos affected by cervid babesiosis, so we also collected postmortem samples from five species of bovids ( n=7) at the Toronto Zoo that died or were euthanized during this time. We detected B. odocoilei in 1% (2/142) of farmed red deer ( Cervus elaphus) as well as in 3% (1/29) of captive wapiti and 4% (3/68) of wild white-tailed deer. Tissues from all zoo bovids and caribou, zoo and wild moose ( Alces alces), and farmed white-tailed deer, wapiti-red deer hybrids, and fallow deer ( Dama dama), tested negative for B. odocoilei. No clinical cases of babesiosis were encountered during this study. These findings suggest that white-tailed deer are a potential natural wildlife reservoir for B. odocoilei in Ontario and that red deer and wapiti could serve as more-localized reservoirs.
巴贝斯氏奥氏虫（Babesia odocoilei）是一种通过蜱传播的白尾鹿（Odocoileus virginianus）原生动物血寄生虫，在北美圈养的鹿科动物中，它作为疾病病因越来越受到关注。巴贝斯氏奥氏虫在美国东南部白尾鹿这一自然野生动物宿主中一直存在地方性流行，最近在美国中北部和东北部以及加拿大的几个省份，它与圈养的欧亚苔原驯鹿（Rangifer tarandus tarandus）、马鹿（Cervus canadensis）和林地驯鹿（Rangifer tarandus caribou）的溶血性贫血有关。巴贝斯氏奥氏虫的出现可能与蜱传播媒介肩突硬蜱（Ixodes scapularis）分布范围的向北扩展有关，也可能与鹿科动物的迁移有关。在加拿大安大略省多伦多动物园的驯鹿和马鹿发生疾病暴发后，我们采用前瞻性尸检调查，通过对脾脏样本进行聚合酶链反应（PCR）和DNA测序，来调查2016 - 2018年安大略省野生、养殖和动物园鹿科动物（n = 270）中巴贝斯氏奥氏虫的流行情况。在受鹿科动物巴贝斯虫病影响的动物园中，有人提出动物园中的牛科动物可能是巴贝斯氏奥氏虫的潜在宿主，所以我们还从多伦多动物园在此期间死亡或被安乐死的5种牛科动物（n = 7）中采集了尸检样本。我们在1%（2/142）的养殖马鹿（Cervus elaphus）、3%（1/29）的圈养马鹿以及4%（3/68）的野生白尾鹿中检测到了巴贝斯氏奥氏虫。所有动物园牛科动物和驯鹿、动物园和野生驼鹿（Alces alces）以及养殖白尾鹿、马鹿 - 马鹿杂交种和黇鹿（Dama dama）的组织，巴贝斯氏奥氏虫检测均为阴性。在本研究期间未遇到巴贝斯虫病的临床病例。这些发现表明，白尾鹿是安大略省巴贝斯氏奥氏虫的潜在自然野生动物宿主，而马鹿和马鹿可能是更本地化的宿主。
