Epidemiological Investigation Of Viral Diarrhea, Bluetongue Disease, Leukemia And Brucellosis In Yanbian Cattle

Yanbian Yellow Cattle is a breed both for beef and labor in Yanbian Korean Autonomous Prefecture of Jilin Province,and is also one of the national resource protection breeds and five local improved breeds of cattle in China considering its unique breed characteristics and excellent meat quality.The infection of bovine viral diarrhea virus(BVDV)causes clinical symptoms such as respiratory diseases,diarrhea,reproductive dysfunction,abortion of pregnant cows,growth retardation,immunosuppression.Bluetongue(BT)is an arbovirus disease that can be transmitted by insects like culicoides.Its clinical symptoms mainly present the edema in mouth and tongue in affected animals,and ulcerative inflammation would appear in these parts and gastrointestinal mucosa in the later stages.Fetuses suffering from the disease could be deformed,and the affected juvenile could be dysplastic or even dead.After infection by bovine leukosis virus(BLV),the most of infected cattle show no typical clinical symptoms,and the main symptoms depend on affected organs.The clinical symptoms vary greatly as the development of the disease due to mechanical injury and compression of tumor cause corresponding symptoms.Brucellosis is a zoonotic infectious disease that mainly affects the reproductive system.It causes abortion,premature delivery,and placenta retention in female animals,whose amniotic fluid and secretions also contain a large number of infections Brucella spp.While male animals show orchitis,arthritis and nerve injury.With the increasing demand of beef and dairy products,the number of livestock breeding and the frequency of imports and exports have increased,resulting in an increasing trend of disease outbreaks,thus seriously threatening the local public health.In the first part of this study,a total of 627 serum samples from three areas of Yanbian Korean Autonomous Prefecture were collected,in which the Enzyme-Linked Immuno sorbent Assay(ELISA)was used for serological test to detect antibodied against bluetongue virus.The results showed that the positive rate of BVD ranged from 40.26%(93/231)to 51.67%(139/269),the average positive rate was 44.82%(281/627),the highest prevalence was confirmed in cattle herds in Yanji,and the sero-prevalent rate was 1.7 times higher than that in Hunchun(OR=1.702).According to the assessment of risk factors,only region was correlated with the positive rate(P<0.05),while there were in significant differences in gender,age and season factors.In all samples,the average positive rate of antibodies of bluetongue was 12.76%(80/627),of which the highest was 14.72%(34/231)in Longjing,13.38%(36/269)in Yanji,and the lowest was 7.87%(10/127)in Hunchun.And the average positive rate of bovine leukemia was 29.35%(184/627),and 17.47%(47/269),16.54%(21/127),15.58%(36/231)in cattle herds in Yanji,Longjing and Hunchun respectively.The risk factors of the two diseases were analyzed,and the results showed that there was no significant difference in the four factors.In the second part of this study,real-time quantitative PCR was used to detect Brucella spp in samples and the risk factors associated with the prevalence of brocellosis were evaluated.The results showed that the positive rate of the disease was 7.34%(46/627)among the selected bovine herds,The positive rates in different regions ranged from 6.06%(14/231)to 8.17%(22/269).The analysis of risk factors showed that there was in significant statistical difference in area,gender,age or season factors.In summary,there have Bovine viral diarrhea,Bluetongue,Bovine leukosis and Brucellosis prevalent in widespread Yanbian Prefecture,Jilin Province,which with mixed infection at the same time.Besides,the potential harm is more serious.Among the Yanbian Yellow Cattle investigated in Yanji city,Hunchun City and Longjing City,the highest antibody detection rate was the prevalence of Bovine viral diarrhea,which was 44.82%.Moreover,the regional differences are also significant.There are no significant regional differences in the prevalence of Bluetongue;Bovine leukosis,and Brucellosis.According to the research,there was no obvious differences in the prevalence of these four diseases in age,gender and season.