| The infectious serositis of geese,also named geese Riemerella anatipestifer(RA)infection,is caused by Riemerella anatipestifer.Goose is acutely or chronically infected as well as duckling.The characterization of lesion is mainly that the fibrous exudate deposits on the surface of animal organs,which result in fibrinous pericarditis,perihepatitis,air sacculitis,arthritis and salpingitis,etc.In recent years,goose infectious serositis has become a severe epidemic disease in goose breeding industry in Gaoyou,Yangzhou.The city of Gaoyou is the key farming district of Yangzhou geese and Gaoyou ducks.The research of incidence as well as prevention and control measures is beneficial for the development of Yangzhou goose and Gaoyou duck breeding industries,which will provide reference for clinical prevention and treatment of goose infectious serositis.In this study,the epidemiological investigation proceeded in 4 farms with suspected goose infectious serositis in Gaoyou during April to June 2020.The separation of bacteria was processed aseptically using geese samples,and then the separated bacteria were identified by mass spectrometry technology.The drug resistance of separated bacteria was detected by K-B disc diffusion method.Finally,the animal regression test was carried out using the strain isolated from farm 1 and the histopathological change of goose was observed.The results of this study were reported as follows:1.The prevalence of infectious serositis in goose:The epidemiological investigation of 4 goose farms with infectious serositis was carried out from April to June 2020.The goslings suffered from RA infection at the age of 6～15 days with 31.6%～43%morbidity,37%～49.8%case fatality and 12.2%～19.6%mortality.All dissected geese had fibrinous pericarditis,hepatitis and air sacculitis.It was effective to treat cases of goose infectious serositis in 4 farms and prevent the whole group with enrofloxacin.2.The isolation and identification of the pathogen of infectious serositis in goose:The samples of dying or dead geese brain,liver,spleen and so on from 4 goose farms with infectious serositis were used to isolate and cultivate pathogen on sheep blood agar plates,incubated at 37℃ for 18-24h in a candle jar.The bacterial identification was detected by mass spectrometry identification technology.The results showed that all isolated bacteria from 4 farms were RA.3.The drug sensitivity test of the pathogen of goose infectious serositis:The drug sensitivity test was carried out on the strains isolated from 4 goose farms by K-B disc diffusion method.12 kinds of antibiotics were used to test.The results showed that most RAs were highly sensitive to gentamicin,enrofloxacin and ceftriaxone,and moderately sensitive to streptomycin,amikacin,amoxicillin,doxycycline,ciprofloxacin and florfenicol,but they were resistant to cephalexin,polymyxin B and compound sulfamethoxazole.4.The animal regression test of the pathogen of goose infectious serositis:Enriched RAs(1×107CFU/mL、1×109CFU/mL、1×1011CFU/mL)were obtained from farm 1 and inoculated to 13-day goslings of Yangzhou goose.They were divided into low-dose group,medium-dose group and high-dose group.The results showed that the medium-dose and high-dose groups are more pathogenic to geese.The high-dose and medium-dose groups reached the peaks of morbidity and mortality after 2～3 days.The morbidity rate was 100%and 80%,as well as the mortality rate was 90%and 60%,respectively.The dissection showed that serositis symptoms,such as liver capsule turbidity,peritoneal turbidity and air sac turbidity.The high-dose and medium-dose groups had severer damage to the goose liver.The liver of high-dose group showed a cord-like structure,and hepatocytes occurred mild or moderate vacuolar degeneration in the pathologic tissue section.What’s more,the inflammatory cell infiltration was around the liver vessels in the medium-dose group. |
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