Beginning in the early 1900s, poly‐factorial, poly‐microbial pneumonia was identified as a disease affecting bighorn sheep (Ovis canadensis) and it continues to threaten bighorn populations, posing an ongoing management challenge. In May and June 2013, a pneumonia outbreak linked to the pathogen Mycoplasma ovipneumoniae led to an all‐age die‐off of desert bighorn sheep (O. c. nelsoni) at Old Dad Peak in the Kelso Mountains of the Mojave Desert in California, USA. Subsequently, we observed clinical signs of respiratory disease among bighorn sheep in multiple neighboring ranges. Our objective was to investigate post‐outbreak survival of adult female bighorn across 9 populations from 2014 to 2017 in the Mojave Desert and evaluate the relationship between M. ovipneumoniae infection and survival, while testing effects of range factors that could potentially influence differences in adult female survival (i.e., forage quality, winter precipitation, population abundance). We fitted adult females with radio‐collars following the outbreak and collected serum and nasal swab samples for competitive enzyme‐linked immunosorbent assay (cELISA) and polymerase chain reaction (PCR) testing to determine exposure and infection status at time of capture. We tracked survival of 115 adult females with radio‐collars and used the known‐fate model in Program MARK to evaluate effects and estimate survival from November 2013 to March 2017. Annual survival was negatively correlated with positive infection status at capture but varied across populations with respect to differences in range conditions. Summer and autumn forage quality, as represented by mean normalized difference vegetation index (NDVI) values for summer and autumn, was positively correlated with overwinter survival, whereas winter precipitation (a proxy for winter severity) was negatively correlated with overwinter survival. Population abundance was negatively correlated with annual survival, suggesting a potential density‐dependent effect. Model‐averaged annual survival estimates ranged from 0.700 ± 0.07 (SE) to 0.945 ± 0.026 for infected individuals and 0.896 ± 0.03 to 0.983 ± 0.011 for uninfected individuals. We conclude that summer and autumn forage quality, indexed by NDVI, may partially offset the negative effect associated with M. ovipneumoniae infection on host survival. Our survival modeling results suggest that chronic infection may have afflicted adult females that were PCR‐positive (i.e., infected with M. ovipneumoniae) at time of capture. We propose programmatic re‐testing of infected individuals to assess pathogen persistence at the individual level and evaluate whether selective culling might potentially help to reduce prevalence and transmission within populations. © 2020 The Wildlife Society.

中文翻译：

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肺炎流行后成年雌大角羊的生存

从1900年代初开始，多因素，多微生物肺炎被认为是一种影响大角羊（Ovis canadensis）的疾病，它继续威胁着大角羊种群，构成了持续的管理挑战。2013年5月和6月，与病原体支原体支原体相关的肺炎暴发导致加利福尼亚莫哈韦沙漠凯尔索山的老爸爸峰的大角羊（O. c。nelsoni）死亡。美国。随后，我们在多个相邻范围的大角羊中观察到呼吸系统疾病的临床体征。我们的目的是调查2014年至2017年莫哈韦沙漠中9个种群中成年雌性大角牛暴发后的生存情况，并评估两者之间的关系。猪肺炎支原体感染和生存，同时测试可能影响成年女性生存差异的范围因素的影响（即，饲草质量，冬季降水，人口数量）。暴发后，我们为成年雌性配备了放射性项圈，并收集了血清和鼻拭子样本，用于竞争性酶联免疫吸附测定（cELISA）和聚合酶链反应（PCR）测试，以确定捕获时的暴露和感染状况。我们追踪了115名具有放射性领的成年女性的存活率，并使用MARK计划中的已知命运模型评估了效果并估计了2013年11月至2017年3月的存活率。年存活率与捕获时的阳性感染状况呈负相关，但在不同人群之间存在差异关于范围条件的差异。夏秋季饲草质量 以夏季和秋季的平均归一化差异植被指数（NDVI）值表示，与越冬存活率呈正相关，而冬季降水（代表冬季严重程度）与越冬存活率呈负相关。人口丰度与年生存率呈负相关，表明存在潜在的密度依赖性效应。模型的年平均生存估计值范围从0.700±0.07（SE）到0.945±0.026（受感染的个体）和0.896±0.03（0.983±0.011）（未感染的个体）。我们得出结论，以NDVI为指标的夏季和秋季饲草质量可能部分抵消了与 而冬季降水（代表冬季严重程度）与越冬生存率呈负相关。人口丰度与年生存率呈负相关，表明存在潜在的密度依赖性效应。模型的年平均生存估计值范围从0.700±0.07（SE）到0.945±0.026（受感染的个体）和0.896±0.03（0.983±0.011）（未感染的个体）。我们得出结论，以NDVI为指标的夏季和秋季饲草质量可能部分抵消了与 而冬季降水（代表冬季严重程度）与越冬生存率呈负相关。人口丰度与年生存率呈负相关，表明存在潜在的密度依赖性效应。模型的年平均生存估计值范围从0.700±0.07（SE）到0.945±0.026（受感染的个体）和0.896±0.03（0.983±0.011）（未感染的个体）。我们得出结论，以NDVI为指标的夏季和秋季饲草质量可能部分抵消了与 对于未感染的个体，为03至0.983±0.011。我们得出结论，以NDVI为指标的夏季和秋季饲草质量可能部分抵消了与 对于未感染的个体，为03至0.983±0.011。我们得出结论，以NDVI为指标的夏季和秋季饲草质量可能部分抵消了与猪肺炎支原体感染对宿主存活的影响。我们的生存模型结果表明，慢性感染可能折磨了捕获时呈PCR阳性的成年女性（即感染了卵形支原体）。我们建议对感染的个体进行程序化重新测试，以评估个体水平上的病原体持久性，并评估选择性剔除是否可能有助于减少人群中的流行和传播。©2020野生动物协会。