Detection and molecular typing of epidemic Brucella strains among camels, sheep, and cattle in Xinjiang, China

by Liu Xingxing, Guangzhen Shi, Lidan Li, Rui Zhang, Jun Qiao

Brucellosis is a zoonotic disease that can result in symptoms including infertility, abortion, testicular inflammation, and arthritis in affected sheep and cattle. The disease can spread through a range of mechanisms, making outbreaks difficult to control such that affected farms often suffer severe economic losses. In addition, humans can be affected by brucellosis, and the number of cases continues to rise annually. As rates of brucellosis in Xinjiang, China have been increasing substantially in recent years, this study was developed to assess brucellosis seroprevalence among herds of cattle, sheep, and camels in Xinjiang through the use of common diagnostic procedures like the Rose Bengal test (RBT) and PCR. A cross-sectional approach was used to analyze the seroprevalence of brucellosis across 720 total farm animals (320 camels, 250 sheep, and 150 cattle). RBT incidence rate for brucellosis was detected in 60 serum samples, 14 (4.38%) from camels, 45 (18%) from sheep, and 1 (0.67%) from cattle. PCR was performed as a confirmatory approach for these RBT-positive samples, with 55 ultimately being confirmed to be positive 13 (4.06%), 41 (16.4%), and 1 (0.67%) samples from camels, sheep, and cattle, respectively. In this survey, sheep exhibited the highest brucellosis seroprevalence using these two analytical techniques, while cattle exhibited the lowest seroprevalence and camels exhibited an intermediate rate. AMOS-PCR analyses identified Brucella melitensis as the unknown bacterium in some of these samples. These results offer new insight regarding brucellosis seroprevalence among farm animals that can be used to formulate more appropriate prevention and control policies, while also improving awareness of epidemic prevention efforts, the need for routine quarantine and disinfection, the benefits of scientific breeding and management, and approaches to improving breeding efficiency for the camel, cattle, and sheep industries.