| In recent years,with the continuous expansion of the scale of pig breeding in our province,the situation of disease prevention and control is becoming more and more severe,the most common viral infection,such as swine fever(CSF),porcine reproductive and respiratory syndrome(PRRS),pseudorabies(PR)and porcine circovirus disease(PCVAD)occur in various farms,these pathogens are not only clinically manifested as separate infections,but also multiple infections or mixed infections,It has brought huge losses to the pig industry.Vaccination is the most important means to prevent and control swine viral infections,prompt vaccination after detection of antibody levels in the body can control the vaccine immune effect,understand the ability of pigs to resist disease,take timely and effective measures to prevent and control epidemics,thus playing an important role in ensuring the health of the pig herd.This study intends to use PCR or RT-PCR methods and ELISA methods,detection of pathogen infection and antibody detection after vaccine immunization from samples from different regions of Shaanxi Province,understand the epidemiological characteristics and vaccine immunization of CSF,PRRS,PR and PCVD in our province,provide a basis for the development of scientific and reasonable prevention and control measures.The study obtained the following results:1.From March 2017 to February 2019,tissue samples from 479 clinically-infected pigs collected in different regions of our province were investigated by PCR or RT-PCR,the results show,the total positive rates of CSFV,PRRSV,HP-PRRSV,PRV and PCV2 in the 479 samples tested were 45.2%,12.7%,47.2%,36.5% and 67.4%,respectively.Among them,the positive rates in Xi’an were 36.9%,15.5%,49.5%,20.6% and 50.5%,respectively.The positive rates in Hanzhong were 59.3%,8.6%,67.9%,38.3% and 82.7%,respectively.The rates were 41.7%,19.4%,50.7%,13.4% and 47.8%,respectively.The positive rates in Yulin were 59.6%,5.9%,35.4%,39.7%,and 71.3%,respectively.The positive rates in Weinan were 22.8%.18.5%,41.3%,65.2%,81.5%.The positive rates in spring were 45.4%,13.8%,53.1%,36.9%,and 61.5%,respectively.The positive rates in summer were 31%,11.2%,46.6%,43.1%,and 62.9%,respectively.The positive rates in autumn were 47.6%.9.9%,46.2%,37.1%,and 78.3%,the positive rates of the four pathogens in winter were 58.9%,17.8%,41.1%,26.7%,and 64.4%,respectively.Among the 479 samples,the mixed infection rate of 2 or more pathogens was 79.5%,of which the double infection rate was 50.9%,the triple infection rate was 25.1%,and the quadruple infection rate was 3.5%,the mixed infection rate of HP-PRRSV and PCV2 was the highest,at 12.9%.2.At the same time,the sera of 479 clinically-infected pigs were tested by ELISA.The results showed that the total positive rates of CSFV,PRRSV,PRV and PCV2 were 47.3%,60.5%,36.1% and 69.1%,respectively.Among them,the positive rates in Xi’an were 37.9%,63.1%,18.4% and 51.5%,respectively.The positive rates in Hanzhong were 59.3%,64.2%,39.5% and 85.2%,respectively,and the positive rates in Xianyang were 41.7%.70.1%,13.4% and 47.8%,the positive rates in Yulin were 61%,44.1%,40.4%,and 74.3%,respectively.The positive rates in Weinan were 29.3%,58.7%,63%,and 82.6%,respectively.The positive rates in spring were 47.7%,75.4%,39.2%,and 63.8%,respectively.The positive rates in summer were 36.6%,58.6%,40.5%,and 65.5%,respectively.The positive rates in autumn were 41.5%,59.4%,and 33.6%,respectively.And 79.7%,the positive rates in winter were 61.1%,43.3%,30% and 64.4%,respectively.The mixed infection rate of two or more pathogens was 86%,of which the double infection rate was 57.8%,the triple infection rate was 24.4%,the quadruple infection rate was 3.8%,and the mixed infection rate of PRRSV and PCV2 was the highest,being 16.3%.3.The ELISA method was used to detect the antibody positive rate of pigs after immunization from March 2017 to February 2019.The results showed that the positive rates of CSFV,PRRSV,PRV and PCV2 antibodies were 78.9%,86.1% and 74.5%,respectively.,77.4%.The positive rate of spring antibody in CSFV was the highest,83.9%,and the lowest in winter,the positive rate was 69.5%.The positive rate of PRRSV autumn antibody was 90.3%,and the positive rate of antibody in winter was the lowest,which was 75.1%.The positive rate of PRV autumn antibody was the highest,which was 85.3%,and the positive rate of antibody in summer was the lowest,which was 67.8%.The positive rate of PCV2 antibody in summer was 86.7%,and the positive rate of antibody in spring was the lowest,70.8%.The antibody positive rate of pigs at each stage was investigated.The positive rate of CSFV antibody was 59.2% for nursery pigs,72.7% for reserve pigs,74.7% for suckling pigs,79.9% for finishing pigs,and 88.9% for sows.The positive rates of PRRSV antibodies were 69.9% for nursery pigs,80.9% for suckling pigs,86.3% for fattening pigs,89.9% for sows,and 92% for reserve pigs.The positive rates of PRV antibodies were 65.3% for suckling pigs,72.3% for sows,72.6% for nursery pigs,79.5% for finishing pigs,and 80.3% for reserve breeding pigs.The positive rates of PCV2 antibody were 66.5% for suckling pigs,71.8% for nursery pigs,77.9% for sows,80.3% for reserve pigs,and 82.7% for finishing pigs.The positive rates of CSFV antibodies in Xi’an,Hanzhong,Xianyang,Yulin and Longnan were 79.9%,77.5%,87.6%,77.7%,and 72.7%,respectively.The positive rates of PRRSV antibodies were 85.9%,85.6%,76.1%,86.8%,and 93.6,respectively.The positive rates of %,PRV antibodies were 71.3%,74.7%,72.3%,69.1%,and 81%,respectively.The positive rates of PCV2 antibodies were 69.2%,83.8%,82.7%,82.5%,and 72.5%,respectively.The infection status survey also used PCR or RT-PCR detection method and ELISA detection method,and the results of the two detection methods were mutually confirmed,the test results show that the infection rates detected by the two methods are basically the same.The four pathogens are prevalent in Xi’an,Hanzhong,Xianyang,Yulin and Weinan;CSF and PRRS occur mostly in winter,HP-PRRS occurs mostly in spring,and PCVAD occurs mostly in autumn;both tests show that mixed infection is very serious.The antibody test results after vaccine immunization showed that the positive rate of antibody of 4 pathogens in Shaanxi Province reached more than 70%,which was in line with the national mandatory immunization antibody positive rate standard(70%).However,the antibody positive rate was not up to standard in all seasons,regions and stages,and the antibody dispersion was high,and the antibody uniformity was poor,it is indicated that the CSF,PRRS,PR and PCVAD vaccine immunization of some pigs in Shaanxi Province failed to achieve complete protection effect. |
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