George Janet L, Martin Daniel J, Lukacs Paul M, Miller Michael W
Colorado Division of Wildlife, 6060 Broadway Street, Denver, Colorado 80216, USA.
J Wildl Dis. 2008 Apr;44(2):388-403. doi: 10.7589/0090-3558-44.2.388.
A pneumonia epidemic reduced bighorn sheep (Ovis canadensis) survival and recruitment during 1997-2000 in a population comprised of three interconnected wintering herds (Kenosha Mountains, Sugarloaf Mountain, Twin Eagles) that inhabited the Kenosha and Tarryall Mountain ranges in central Colorado, USA. The onset of this epidemic coincided temporally and spatially with the appearance of a single domestic sheep (Ovis aires) on the Sugarloaf Mountain herd's winter range in December 1997. Although only bighorns in the Sugarloaf Mountain herd were affected in 1997-98, cases also occurred during 1998-99 in the other two wintering herds, likely after the epidemic spread via established seasonal movements of male bighorns. In all, we located 86 bighorn carcasses during 1997-2000. Three species of Pasteurella were isolated in various combinations from affected lung tissues from 20 bighorn carcasses where tissues were available and suitable for diagnostic evaluation; with one exception, beta-hemolytic mannheimia (Pasteurella) haemolytica (primarily reported as biogroup 1(G) or 1(alphaG)) was isolated from lung tissues of cases evaluated during winter 1997-98. The epidemic dramatically lowered adult bighorn monthly survival in all three herds; a model that included an acute epidemic effect, differing between sexes and with vaccination status, that diminished linearly over the next 12 mo best represented field data. In addition to the direct mortality associated with epidemics in these three herds, lamb recruitment in years following the pneumonia epidemic also was depressed as compared to years prior to the epidemic. Based on observations presented here, pasteurellosis epidemics in free-ranging bighorn sheep can arise through incursion of domestic sheep onto native ranges, and thus minimizing contact between domestic and bighorn sheep appears to be a logical principle for bighorn sheep conservation.
1997年至2000年期间，在美国科罗拉多州中部基诺沙山脉和塔里尔山脉的一个由三个相互连接的越冬羊群（基诺沙山、糖面包山、双鹰）组成的种群中，一场肺炎疫情降低了大角羊（加拿大盘羊）的存活率和繁殖率。这场疫情的爆发在时间和空间上与1997年12月出现在糖面包山羊群冬季牧场的一只家养绵羊（绵羊）的出现相吻合。虽然在1997 - 1998年只有糖面包山羊群的大角羊受到影响，但在1998 - 1999年其他两个越冬羊群中也出现了病例，这可能是疫情通过成年雄性大角羊既定的季节性迁徙传播之后发生的。在1997年至2000年期间，我们总共找到了86具大角羊尸体。从20具大角羊尸体的受影响肺组织中以各种组合分离出了三种巴斯德氏菌，这些组织可用且适合进行诊断评估；除了一个例外，在1997 - 1998年冬季评估的病例的肺组织中分离出了β - 溶血曼氏（巴斯德氏）杆菌（主要报告为生物群1(G)或1(αG)）。疫情显著降低了所有三个羊群中成年大角羊的月存活率；一个包含急性疫情效应的模型，该效应在性别和疫苗接种状态上有所不同，并在接下来的12个月内呈线性下降，最能代表实地数据。除了这三个羊群中与疫情相关的直接死亡率外，与疫情前的年份相比，肺炎疫情后的几年里羊羔的繁殖率也有所下降。基于此处呈现的观察结果，自由放养的大角羊中的巴氏杆菌病疫情可能通过家养绵羊侵入原生范围而引发，因此尽量减少家养绵羊和大角羊之间的接触似乎是大角羊保护的一个合理原则。
