| Classical swine fever (CSF) is an important disease in pigs caused by the CSF virus (CSFV), which belongs to the genus Pestivirus within the family Flaviviridae. The disease is characterized by a peracute, acute, subacute, chronic, atypical, or inapparent course. In recent years,epidemic situation of CSF in China have taken great changes,atypical CSF were prominent clinical signs.Atypical CSF is caused by low virulent strains is more difficult to recognize, and this favors the spread of these strains. These atypically infected pigs are important in the epidemiology of the disease because they act as sources of infection in susceptible pigs. To make clear of the cause for the atrpical CSF, some researches were performed.A epidemiologic investigation of classical swine fever(CSF) was conducted in 12 CSFV infected pig farms from 5 districts in Shanghai.The results showed that the clinical symptoms of sick pigs in the type of atypical CSF(reproductive syndrome or mild syndrome). Samples of brain, lung, liver, kidney, spleen,heart,tonsil, lymph node, small and large intestines ,sperm and whole blood were collected from infected pigs,and detected the distribution of CSFV in different samples using ELISA(IDEXX),the results showed the CSF virus were prominent in samples of brain, kidney, spleen,,tonsil, lymph node,and whole blood.An antigen detection against classical swine fever(CSF) was performed by CSFV antigen ELISA(IDEXX) in different ages of pigs in Shanghai large-scaled farms. 238 whole blood samples of 20 swine farms from 6 districts and 1 county in Shanghai were detected for CSF and bovine viral diarrhea(BVD) by using ELISA technique.The results were as follows. The population positive rates in different ages of pigs (breeder,suckling pigs, nursery pigs and grower-finisher)were 23.5%, 1.68 % ,2.52% and 7.14%,and The population positive rate of BVD only in finisher pigs. The serological detection results were correspondence with those of epidemiologic investigation . |
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