Olafson Pia U, Thomas Donald B, May Melinda A, Buckmeier Beverly G, Duhaime Roberta A
1 US Department of Agriculture-Agricultural Research Service, Knipling-Bushland Livestock Insects Research Laboratory, 2700 Fredricksburg Road, Kerrville, Texas 78028, USA.
2 US Department of Agriculture-Agricultural Research Service, Cattle Fever Tick Research Laboratory, 22675 N Moorefield Road, Moore Air Base, Edinburg, Texas 78541, USA.
J Wildl Dis. 2018 Oct;54(4):734-744. doi: 10.7589/2017-09-239. Epub 2018 Jun 4.
Nilgai ( Boselaphus tragocamelus) are nonnative bovines that were originally introduced as game animals to one large, south Texas, US ranch but that are now present throughout southeastern Texas from Baffin Bay to Harlingen and in northern Mexico at least as far west as Durango. Between October 2014 and January 2017, nilgai ( n=517) were examined for the presence of tick ectoparasites, with particular interest in the cattle fever tick, Rhipicephalus ( Boophilus) microplus. These animals were either hunter killed or they were culled as part of federal cooperative harvesting from Cameron and Willacy counties in southeastern Texas. The proportion of fever tick-infested animals differed in a N-to-S pattern, and this was at least partly attributed to differences in habitat. The southern area is a lowland floodplain predominated by halophytes, whereas the northerly area is upland thorn scrub, the latter of which provides a vegetative canopy that is more conducive to tick survival and persistence. A subset of nilgai, all from the Texas-Mexico border area, were screened for livestock pathogens using molecular and serological assays. All nilgai were seronegative for Babesia ( Theileria) equi and Babesia cabalii. Although 11 animals were seropositive for Anaplasma marginale by competitive enzyme-linked immunosorbent assay (cELISA), these were interpreted with caution because of the lack of concordance between cELISA and molecular detection assays. All animals were PCR negative for presence of Babesia spp. DNA, and a single nilgai was seropositive for Babesia bovis and Babesia bigemina by complement fixation. It remains unknown whether cattle Babesia spp. can establish an infection in nilgai.
蓝牛羚（Boselaphus tragocamelus）是外来牛种，最初作为猎物被引入美国得克萨斯州南部的一个大牧场，但现在在得克萨斯州东南部从巴芬湾到哈林根一带均有分布，在墨西哥北部至少远至杜兰戈也有出现。2014年10月至2017年1月期间，对517只蓝牛羚进行了蜱外寄生虫检查，特别关注牛蜱热蜱（微小牛蜱，Rhipicephalus (Boophilus) microplus）。这些动物要么是被猎人捕杀，要么是作为得克萨斯州东南部卡梅伦县和威拉西县联邦合作捕猎的一部分被扑杀。感染热蜱的动物比例呈北向南递减模式，这至少部分归因于栖息地差异。南部地区是一个以盐生植物为主的低地洪泛平原，而北部地区是高地多刺灌丛，后者提供了更有利于蜱生存和繁衍的植被覆盖。对所有来自得克萨斯州与墨西哥边境地区的一部分蓝牛羚，使用分子和血清学检测方法筛查家畜病原体。所有蓝牛羚对马巴贝斯虫（泰勒虫，Babesia (Theileria) equi）和卡巴利巴贝斯虫（Babesia cabalii）血清学检测均为阴性。尽管通过竞争酶联免疫吸附测定（cELISA）有11只动物对边缘无形体（Anaplasma marginale）血清学检测呈阳性，但由于cELISA与分子检测方法结果不一致，对这些结果需谨慎解读。所有动物巴贝斯虫属（Babesia spp.）DNA的聚合酶链反应（PCR）检测均为阴性，有一只蓝牛羚通过补体结合试验对牛巴贝斯虫（Babesia bovis）和双芽巴贝斯虫（Babesia bigemina）血清学检测呈阳性。牛巴贝斯虫属能否在蓝牛羚体内建立感染仍不清楚。
