Muma J B, Samui K L, Oloya J, Munyeme M, Skjerve E
Department of Disease Control, University of Zambia, School of Veterinary Medicine, Lusaka, Zambia.
Prev Vet Med. 2007 Aug 16;80(4):306-17. doi: 10.1016/j.prevetmed.2007.03.003. Epub 2007 May 3.
We conducted this cross-sectional study to investigate risk factors of Brucella seropositivity in cattle herds reared in livestock-wildlife interface areas of Blue Lagoon and Lochinvar National Parks in Zambia between August 2003 and September 2004. Sera were collected from cattle aged > or =2 years from 124 herds. Data on husbandry practices, grazing strategies, and herd structure (sex and age composition) were also collected. Sera were screened for anti-Brucella antibodies using the Rose Bengal test (RBT) as a presumptive test and a competitive-ELISA (c-ELISA) as a confirmatory test. A herd was classified as Brucella seropositive if at least one animal tested positive on both RBT and c-ELISA in series testing. Risk factors for herd-level brucellosis seropositivity were tested using multivariable logistic regression; risk factors for increases in the within-herd counts of seropositive cattle were analyzed using the negative binomial regression model with the number of seropositive animals as outcome and total number of cattle tested in a herd as the population at risk (exposure). Of the 110 herds tested, 68 (62; 95% CI: 53, 71% after adjusting for clustering by area) tested seropositive for exposure to Brucella spp. The final logistic-regression model identified geographical area, with Lochinvar (OR=3.4; CI: 0.97, 12) and Kazungula (OR=4.3; CI: 0.91, 20) recording higher odds of Brucella infections compared to Blue Lagoon. Herds coming in contact with wildlife had higher odds compared to those without contact (OR=3.4; CI: 1, 11). Similarly, the odds of Brucella infection were progressively higher in the larger herd categories (26-40 cattle, OR=2.6; CI: 0.70, 10; 41-82 cattle, OR=4.9; CI: 0.93, 26; >82 cattle, OR=9.4; CI: 1.7-51) compared to the smallest herd category (10-25). The negative binomial regression model identified geographical area, contact with wildlife, and herd size as having significant effect on counts of seropositive cattle in a herd.
2003年8月至2004年9月期间，我们开展了这项横断面研究，以调查赞比亚蓝湖和洛钦瓦尔国家公园牲畜与野生动物交界地区饲养的牛群中布鲁氏菌血清阳性的风险因素。从124个牛群中采集了年龄大于或等于2岁的牛的血清。还收集了饲养管理方式、放牧策略和畜群结构（性别和年龄组成）的数据。血清先用虎红试验（RBT）进行布鲁氏菌抗体筛查作为初步检测，然后用竞争酶联免疫吸附测定法（c-ELISA）进行确证检测。如果在系列检测中至少有一头动物的RBT和c-ELISA检测均呈阳性，则该牛群被归类为布鲁氏菌血清阳性。使用多变量逻辑回归分析畜群层面布鲁氏菌病血清阳性的风险因素；使用负二项回归模型分析血清阳性牛群内血清阳性牛数量增加的风险因素，将血清阳性动物数量作为结果，将牛群中检测的牛的总数作为危险人群（暴露）。在检测的110个牛群中，68个（62个；95%可信区间：53，经按地区聚类调整后为71%）检测出布鲁氏菌属暴露血清阳性。最终的逻辑回归模型确定地理区域是一个因素，与蓝湖相比，洛钦瓦尔（比值比=3.4；可信区间：0.97，12）和卡宗古拉（比值比=4.3；可信区间：0.91，20）记录的布鲁氏菌感染几率更高。与未接触野生动物的牛群相比，接触野生动物的牛群感染几率更高（比值比=3.4；可信区间：1，11）。同样，与最小的畜群类别（10 - 25头牛）相比，较大畜群类别（26 - 40头牛，比值比=2.6；可信区间：0.70，10；41 - 82头牛，比值比=4.9；可信区间：0.93，26；大于82头牛，比值比=9.4；可信区间：1.7 - 51）的布鲁氏菌感染几率逐渐升高。负二项回归模型确定地理区域、与野生动物的接触和畜群大小对牛群中血清阳性牛的数量有显著影响。
