Diagnosis And Etiology Of Emerging Or Reemerging Infectious Diseases Of Beef Cattle In Guangxi

In recent years,the Guangxi beef cattle industry maintains a good momentum of growth.But the risk of epidemic diseases is rising as the number and breeding density of cattle grow rapidly.In order to understand the prevalence and occurrence of the disease in Guangxi beef cattle industry and discover emerging infectious diseases or re-emerging infectious diseases that had been severely epidemic controlled in the past but rehabilitate in Guangxi beef cattle industry,in 2018-2019,under the guidance of the disease control expert team of Guangxi beef cattle and sheep,four important epidemic pathogens that may jeopardize the development of the industry were found through clinical consultation,on-site sampling,pathological examination,identification of symptomatic diseases and laboratory diagnosis.The results are now reported as follows:1.Bovine papular stomatitis virus.The symptoms of the sick calves were salivation,oral erosion.Their body temperature was still normal,and no history of foreign body contact or oral injury.Scraping diseased cow gingival erosion congestion hyperplasia and scab skin material,No foot-and-mouth disease virus,viral diarrhea/mucosal disease virus,bovine infectious rhinotracheitis virus and bovine epidemic fever virus were detected by specific PCR assay;A 91 bp band was amplified from the sample of the disease material,then the sequencing result was compared with the gene sequence of Gen Bank’s bovine papular stomatitis virus,showing that their nucleotide homology was 95.56%.It indicated that the sample species contained bovine papular stomatitis virus,and combined with the clinical characteristic symptoms of the calf,it was confirmed that bovine papulitis infected the calf and caused the disease.2.Bovine papilloma virus.The characteristic clinical symptoms of sick cattle are mainly obvious tumors on the skin of the head,neck,and back,protruding from the surface of the skin,varying in size,broccoli-like,the largest tumor can be up to 8 cm in diameter.But mental,appetite,body temperature,et al seemed normal.No parasites were found on the microscopic examination in the tumor,and no bacteria were found on the smear staining microscopic examination.Observation of pathological tissue sections made by tumors showed epidermal and dermal hyperplasia,and the cancer cells were fusiform or star-shaped.The cells in the center of the cancer nest were hyperkeratotic,with a concentric structure forming typical cancer beads.PCR test results showed that the tumor-like material was positive for bovine papillomavirus.3.Shigella bovis.An acute case of high fever,shortness of breath,diarrhea,and bloody stools suddenly occurred in a cattle farm.Before the death of the sick cattle,it showed neurological symptoms that front and back foot strokes as swimming.A strain of Gram-negative bacilli was isolated from the intestines of dead cattle.It was identified as Shigella by phenotypic characteristics,16 s r RNA gene sequence alignment,and biochemical tests.The pathogenicity test of mice was carried out at a concentration of 0.5 M turbidibacteria.All 10 healthy mice inoculated with bacteria died within 24 hours,and the mortality rate was 100%.4.Clostridium perfringens type A.From April to October 2019,acute sudden death cases of cattle occurred in Baise,Hepu,Hechi,Beihai,Nanning and other places in Guangxi.Pathological examination showed that the abdomen significantly swelling,duodenal and jejunal bleeding,mesenteric lymph nodes congestion enlarging and the lungs bleeding.Gram-positive bacilli were isolated from the intestinal mucosa contents of all five cases.The phenotypic characteristics,biochemical tests,and PCR identification of C.perfringens specific primers showed that the bacteria were Clostridium perfringens type A.No bacteria were isolated from other organs.Then healthy mice inoculated with the isolates were all died within 36 hours,with a mortality rate of 100%.The results of vitro antibacterial tests showed that the isolates were sensitive to five drugs-penicillin,cefotaxime sodium,cefradine sodium,ceftriaxone sodium,and ampicillin.Conclusion: By detecting the pathogens of four kinds of cases,and reviewing the domestic and foreign literature,it can be determined that bovine papular stomatitis virus,bovine papilloma virus,and Shigella bovis were the emerging pathogens of beef cattle in Guangxi.Clostridium perfringens type A was re-emerging pathogen in Guangxi beef cattle.These four kinds of pathogens have a certain potential threat to Guangxi beef cattle breeding.The next step of our research will pay attention to further study on etiology and develop new rapid detection technologies to provide technical support for the prevention and control of Guangxi beef cattle disease.