Data from: Disease, predation and demography: assessing the impacts of bovine tuberculosis on African buffalo by monitoring at individual and population levels

1. Understanding the effects of disease is critical to determining appropriate management responses, but estimating those effects in wildlife species is challenging. We used bovine tuberculosis (BTB) in the African buffalo Syncerus caffer population of Kruger National Park, South Africa, as a case study to highlight the issues associated with estimating chronic disease effects in a long-lived host. 2. We used known and radiocollared buffalo, aerial census data, and a natural gradient in pathogen prevalence to investigate if: (i) at the individual level, BTB infection reduces reproduction; (ii) BTB infection increases vulnerability to predation; and (iii) at the population level, increased BTB prevalence causes reduced population growth. 3. There was only a marginal reduction in calving success associated with BTB infection, as indexed by the probability of sighting a known adult female with or without a calf ( P = 0·065). 4. Since 1991, BTB prevalence increased from 27 to 45% in the southern region and from 4 to 28% in the central region of Kruger National Park. The prevalence in the northern regions was only 1·5% in 1998. Buffalo population growth rates, however, were neither statistically different among regions nor declining over time. 5. Lions Panthera leo did not appear to preferentially kill test-positive buffalo. The best (Akaike’s Information Criterion corrected for small sample size) AIC c model with BTB as a covariate [exp( β ) = 0·49; 95% CI = (0·24–1·02)] suggested that the mortality hazard for positive individuals was no greater than for test-negative individuals. 6. Synthesis and applications . Test accuracy, time-varying disease status, and movement among populations are some of the issues that make the detection of chronic disease impacts challenging. For these reasons, the demographic impacts of bovine tuberculosis in the Kruger National Park remain undetectable despite 6 years of study on known individuals and 40 years of population counts. However, the rainfall and forage conditions during this study were relatively good and the impacts of many chronic diseases may be a non-linear function of environmental conditions such that1. 阐明疾病的影响是制定恰当管理对策的核心前提，但在野生生物类群中量化此类影响却极具挑战。本研究以南非克鲁格国家公园（Kruger National Park）内的非洲水牛（*Syncerus caffer*）种群及其感染的牛结核病（bovine tuberculosis, BTB）为案例研究，旨在剖析在长寿命宿主中量化慢性疾病影响时所面临的各类问题。 2. 本研究借助已知个体、佩戴无线电项圈的水牛个体、航空种群普查数据，以及病原体流行率的自然梯度，对以下三个问题展开探究：（i）在个体层面，牛结核病感染是否会降低繁殖成功率；（ii）牛结核病感染是否会提升宿主被捕食的风险；（iii）在种群层面，牛结核病流行率的升高是否会导致种群增长速率下降。 3. 以已知成年雌性水牛是否伴随幼崽的目击概率为指标，与牛结核病感染相关的产犊成功率仅存在微弱降低（P=0.065）。 4. 自1991年起，克鲁格国家公园南部区域的牛结核病流行率从27%升至45%，中部区域则从4%升至28%；而北部区域在1998年的流行率仅为1.5%。但水牛的种群增长速率在区域间并无统计学差异，且未随时间出现下降趋势。 5. 狮子（*Panthera leo*）并未表现出优先捕杀牛结核病检测呈阳性水牛的倾向。以牛结核病为协变量的最优小样本校正赤池信息准则（Akaike’s Information Criterion corrected for small sample size, AICc）模型显示[exp(β)=0.49；95%置信区间CI=(0.24–1.02)]，感染个体的死亡风险并不高于检测阴性的个体。 6. 综合与应用：检测准确性、时变的疾病感染状态，以及种群间的个体移动，均是导致慢性疾病影响难以被检测的关键因素。正因如此，尽管针对已知个体开展了6年的跟踪研究，并积累了40年的种群普查数据，克鲁格国家公园内牛结核病的种群动态影响仍未被探明。不过本研究期间的降雨与牧草条件相对良好，而多数慢性疾病的影响可能是环境条件的非线性函数，使得……