Diagnosis of Bovine Akabane Disease in an Area of Jilin Province
[Objective]In 2022,the suspected case of bovine Akabane disease occurred in a region of Jilin province.To clarify the cause of infected cattle,a diagnosis was conducted on the affected cattle.[Method]Epidemiological investigation and clinical symptom analysis were conducted on the cattle farm,followed by comprehensive diagnosis through laboratory histopathological observation and serological testing.Tissue samples from diseased and dead fetal cows and placental tissue grinding solution from diseased cows were inoculated into Vero cells,SPF chicken embryos,and mouse brains for virus isolation.[Result]The clinical signs were abortion,stillbirth in cow,and congenital anomaly in fetuses.The epidemiological statistical analysis revealed that the empty pregnant rate of local cows was 29％,and the incidence rate of stillbirth and malformed birth of cows was 24％.The infected cows could be pregnant and deliver calves normally.Deformed calves showed congenital arthrogryposis,visual impairment,delayed neurological reactions due to abnormal brain development.The typical lesions of stillborn calves exhitited hydranencephaly syndrome,with abnormal head,malformation of brain and massive hydrocephalus,consistent with the clinical characteristics of Akabane disease.Pathological examination of the brain tissue of deformed calves showed eosinophilic necrosis of neurons,with microglia engulfing necrotic neurons and lymphocytes and monocytes surrounding blood vessels to form a"sheath",which was a typical non suppurative encephalitis and consistent with the pathological characteristics of bovine brain tissue affected by Akabane disease.No viral nucleic acid was detected in the tissue homogenate supernatant and cell culture supernatant of deceased fetal cattle and cow placenta,which might be related to the short duration of viremia caused by Akabane disease.The ELISA antibody test results for the serum Akabane disease in cows and calves with the disease were both positive.[Conclusion]The present results indicated that abortion,stillbirth and calf deformities in the area were associated with Akabane disease.The results of this study providesd experimental data and reference materials for the diagnosis and prevention of Akabane disease.
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