Department of Veterinary Sciences, University of Wyoming, 1174 Snowy Range Road, Laramie, Wyoming 82070, USA.
Wyoming Game and Fish Department, 815 Rockwood Drive, Gillette, Wyoming 82716, USA.
J Wildl Dis. 2022 Jul 1;58(3):524-536. doi: 10.7589/JWD-D-21-00117.
Mycoplasma bovis is an economically important bacterial pathogen of cattle (Bos taurus) and bison (Bison bison) that most commonly causes pneumonia, polyarthritis, and mastitis. It is prevalent in cattle and ranched bison; however, infections in other species are rare. In early 2019, we identified M. bovis in free-ranging pronghorn (Antilocapra americana) in northeastern Wyoming. Here, we report on additional pronghorn mortalities caused by M. bovis, in the same approximately 120-km2 geographic region 1 yr later. Genetic analysis by multilocus sequence typing revealed that the mortalities were caused by the same M. bovis sequence type, which is unique among all sequence types documented thus far in North America. To explore whether pronghorn maintain chronic infections and begin assessing M. bovis status in other sympatric species, we used PCR testing of nasal swabs to opportunistically survey select free-ranging ungulates. We found no evidence of subclinical infections in 13 pronghorn sampled from the outbreak area (upper 95% binomial confidence limit [bCL], ∼24.7%) or among 217 additional pronghorn (upper 95% bCL, ∼1.7%) sampled from eight additional counties in Wyoming and 10 in Montana. All mule deer (Odocoileus hemionus; n=231; upper 95% bCL, ∼1.6%) sampled from 11 counties in Wyoming also were PCR negative. To assess the potential for environmental transmission, we examined persistence of M. bovis in various substrates and conditions. Controlled experiments revealed that M. bovis can remain viable for 6 h in shaded water and 2 h in direct sunlight. Our results indicate that environmental transmission of M. bovis from livestock to pronghorn is possible and that seasonality of infection could be due to shared resources during late winter. Further investigations to better understand transmission dynamics, to assess population level impacts to pronghorn, and to determine disease risks among pronghorn and other ungulate taxa appear warranted.
牛支原体是一种对牛（Bos taurus）和野牛（Bison bison）具有重要经济意义的细菌病原体，最常引起肺炎、多发性关节炎和乳腺炎。它在牛和牧场野牛中流行；然而，其他物种的感染很少见。2019 年初，我们在怀俄明州东北部的自由放养叉角羚（Antilocapra americana）中发现了牛支原体。在这里，我们报告了大约 120 平方公里的地理区域中，1 年后由牛支原体引起的叉角羚额外死亡。通过多位点序列分型的遗传分析表明，这些死亡是由相同的牛支原体序列型引起的，这在北美迄今为止记录的所有序列型中是独特的。为了探索叉角羚是否维持慢性感染，并开始评估其他共生物种中的牛支原体状况，我们使用鼻拭子的 PCR 检测来偶然调查选择的自由放养有蹄类动物。我们在从疫情地区（上限 95%二项置信限[ bCL]，约 24.7%）中选择的 13 只叉角羚中未发现亚临床感染的证据，也未在怀俄明州的八个县和蒙大拿州的 10 个县中选择的 217 只叉角羚（上限 95% bCL，约 1.7%）中发现亚临床感染的证据。从怀俄明州的 11 个县选择的所有骡鹿（Odocoileus hemionus；n=231；上限 95% bCL，约 1.6%）也都是 PCR 阴性。为了评估环境传播的潜力，我们研究了各种基质和条件下牛支原体的持久性。对照实验表明，牛支原体在遮荫的水中可存活 6 小时，在直射阳光下可存活 2 小时。我们的结果表明，牛支原体从牲畜到叉角羚的环境传播是可能的，感染的季节性可能是由于冬季后期共享资源所致。进一步的研究以更好地了解传播动态，评估对叉角羚的种群水平影响，并确定叉角羚和其他有蹄类动物的疾病风险，似乎是有必要的。
