Prev Vet Med. 2014 Jan 1;113(1):47-58. doi: 10.1016/j.prevetmed.2013.09.016.
Disease caused by Brucella spp. represents the most common bacterial zoonotic infection worldwide. The distribution and public health impact of these infections in Nepal's mountain regions are poorly characterized. This cross sectional study assesses the burden of brucellosis on transhumant pastoralists and their yak in and around Shey Phoksundo National Park, Nepal. Objectives were to: (1) estimate individual animal prevalence of Brucella-seropositive yak, (2) identify herd- and individual-level risk factors associated with Brucella seropositivity in individual yak, and (3) identify herd-level risk factors associated with reported human brucellosis-like symptoms in a household. A case of household symptoms was defined as the reported occurrence within the previous year of at least one of three acute symptoms (chills, fever, night chills) and one of two chronic symptoms (joint pain, swollen joint(s)) in one or both of two individuals interviewed in a household. Two-hundred-ninety-seven yak from 61 herds were sampled, and 61 household questionnaires were completed. Estimated true prevalence was 0.22 (95% CI: 0.17; 0.28). Poisson regression with generalized estimating equations was used to account for repeated measures within a cluster (herd). Yak in herds reporting abortion occurrence within the previous year were 2.3 times more likely to be seropositive than those in herds not reporting abortion (95% CI: 1.2; 4.2, p = 0.01). For every 10 animal increase in herd number, individual animal seropositivity risk increased by 30% (95% CI: 10%; 50%, p = 0.001). Male yak were 0.7 times as likely to be seropositive as female yak (95% CI: 0.5; 0.9, p = 0.01). Three to five year old yak were 2 times more likely to be seropositive than yak <3 years old (95% CI: 1.3; 3.2, p = 0.003), and yak >5 years old were 4.9 times more likely to be seropositive than yak <3 years old (95% CI: 2.9; 8.1, p < 0.001). Risk of reported brucellosis-like symptoms at the household level was 2 (95% CI: 1.1; 3.5, p = 0.02) times greater for households with herds with >1 reactor, and was 3.6 (95% CI: 1.4; 9.2, p = 0.008) times greater for households reporting the practice of raw milk consumption. These results indicate that yak seropositivity for Brucella spp. is widespread in the region, and is associated with reported human disease. This epidemiologic understanding is essential to the identification of public health opportunities at the interface of Himalayan livestock populations and the transhumant pastoralists that depend on them.
布鲁氏菌病是由布鲁氏菌引起的疾病，是全球最常见的细菌性人畜共患病。尼泊尔山区这些感染的分布和公共卫生影响特征描述不足。本横断面研究评估了布鲁氏菌病对尼泊尔谢普桑多国家公园及其周边地区迁徙牧民及其牦牛的负担。目的是：（1）估计布鲁氏菌血清阳性牦牛的个体动物患病率；（2）确定与个体牦牛布鲁氏菌血清阳性相关的畜群和个体水平风险因素；（3）确定与家庭中报告的人类类布鲁氏菌病症状相关的畜群水平风险因素。家庭症状的病例定义为在过去一年中，在接受采访的两个家庭中，至少有一个人报告出现了三种急性症状（寒战、发热、夜间寒战）中的一种和两种慢性症状（关节痛、关节肿胀）中的一种。对 61 个畜群的 297 头牦牛进行了采样，并完成了 61 份家庭调查问卷。估计的真实患病率为 0.22（95%CI：0.17；0.28）。使用广义估计方程的泊松回归来解释群内（畜群）的重复测量。在过去一年中报告流产发生的畜群中的牦牛比未报告流产的畜群中的牦牛更有可能呈血清阳性（95%CI：1.2；4.2，p=0.01）。畜群数量每增加 10 头，个体动物血清阳性的风险就会增加 30%（95%CI：10%；50%，p=0.001）。公牦牛血清阳性的可能性是母牦牛的 0.7 倍（95%CI：0.5；0.9，p=0.01）。3 至 5 岁的牦牛比<3 岁的牦牛更有可能呈血清阳性（95%CI：1.3；3.2，p=0.003），而>5 岁的牦牛比<3 岁的牦牛更有可能呈血清阳性（95%CI：2.9；8.1，p<0.001）。家庭层面报告的类布鲁氏菌病症状的风险是畜群中存在>1 个反应牛的家庭的 2 倍（95%CI：1.1；3.5，p=0.02），是报告生奶消费习惯的家庭的 3.6 倍（95%CI：1.4；9.2，p=0.008）。这些结果表明，该地区牦牛对布鲁氏菌属的血清阳性率普遍较高，且与报告的人类疾病有关。这种流行病学认识对于确定喜马拉雅山畜群与依赖它们的迁徙牧民之间的公共卫生机会至关重要。
