Investigation On Immunization And Pathogens Of Four Swine Epidemics In Nanyang City From 2018 To 2020

Nanyang is a place where pig production is more concentrated in China.The scale and intensification of pig industry is getting higher and higher,and the harm of viral infectious diseases to pigs is getting more and more serious.Swine fever(CSF),porcine pseudorabies(PR),porcine reproductive and respiratory syndrome(PRRS)and porcine foot-and-mouth disease(FMD)are still the main diseases affecting the economic benefits of pig farms.It is particularly important to master the immune situation and pathogen carrying situation of pig farms in Nanyang area and do a good job in biosafety management of pig farms.In this study,the status of carrying and immunity of four major epidemic pathogens in the pig population in Nanyang was investigated,and a comprehensive prevention and control scheme of four pig diseases was proposed based on the survey results.which laid a foundation for the healthy development of the pig industry in Nanyang.In this study,antibody detection was performed on pig blood samples submitted from pig farms in 13 counties in Nanyang region during 2018-2020 by commercially available ELISA kit.In 2018,5002,12630,1990,2503,3838 and 6142 pig serum samples were tested for swine fever virus(CSFV),porcine reproductive and respiratory syndrome virus(PRRSV),porcine foot-and-mouth disease virus A(FMDVA),porcine foot-and-mouth disease virus O(FMDVO),and porcine pseudorabies virus GB(GB),respectively.PRVGB and porcine pseudorabies virus GE(PRVGE)antibodies.The results showed that the positive rates of immune antibodies were 88.84%,92.79%,80.80%,90.97%,93.12%,40.21%,respectively.In 2019,2023,2358,1718,1848,699 and 870 pig serum samples were tested for CSFV,PRRSV,FMDVA,FMDVO,PRVGB and PRVGE antibodies.The results showed that the positive rates of immune antibodies were 82.30%,85.50%,70.61%,86.20%,86.98%,59.17%.respectively.In 2020,4766,4718,2676,4179,1191 and 2258 pig serum samples were tested for CSFV,PRRSV,FMDVA,FMDVO,PRVGB and PRVGE antibodies,respectively.The results showed that the positive rates of immune antibodies were 81.58%,77.62%,70.89%,72.89%,88.54%and 18.29%,respectively.The continuous determination of the positive rates of immune antibodies against the four kinds of swine diseases in three years showed that the overall epidemic prevention of the four kinds of pigs in Nanyang area was good,and the positive rates of immune antibodies all exceeded the number of immunized qualified individuals stipulated by the Ministry of Agriculture,accounting for more than 70%(including)of the total population.According to the results of PRVGE antibody detection,the antibody positive rate was higher in 2018 and 2019,indicating that the pressure of Pseudorabies wild virus infection existed in the pig farms in Nanyang area.The difference of antibody positive rate was not obvious in different seasons.The comparison of immune situation in different regions found that the antibody positive rate of swine fever and swine reproductive and respiratory syndrome disease in the western region of Nanyang was relatively high,while the antibody positive rate in the northern Nanzhao mountain area was low.Because the western region of Nanyang was mostly large pig raising enterprises,and the northern mountain area was small self-owned households.It was found that the positive rate of large pig farms was higher than that of small and medium-sized pig farms.In order to understand the pathogens of four swine epidemics in Nanyang city in 2018,2019 and 2020,the real-time fluorescence quantitative PCR method was used to detect the etiology.In this study,samples of pig tissues(tonsil,brain,trigeminal nerve,inguinal lymph node,spleen,swab,lung,kidney)were collected from slaughterhouses,commercial farms,breeding farms and self-employed farmers in 13 counties of Nanyang.A total of 630 pig tissues were detected in 2018,and the positive rate of CSFV nucleic acid was 4.92%.PRRSV nucleic acid positive rate was 50%.PRV nucleic acid positive rate 9.52%;All tests for FMDV were negative.In the 968 samples tested in 2019,the positive rate of CSFV nucleic acid was 5.17%.PRRSV nucleic acid positive rate was 61.16%.PRV nucleic acid positive rate 10.02%;All tests for FMDV were negative.775 samples were detected in 2020,and the positive rate of CSFV nucleic acid was 5.42%.PRRSV nucleic acid positive rate was 70.06%.PRV positive rate was 7.23%.All tests for FMDV were negative.Three years,four kinds of disease pathogen detection,pig foot-and-mouth disease virus are all negative,explain the foot-and-mouth disease prevention and control work more attention to the pig farms,but CSFV,PRV,three years nucleic acid testing PRRSV positive rate increasing,farmers should pay more attention to the three breeding of disease prevention and control,although the test sample as the sample,But there is still a risk of infection outbreaks.The detection rate of PRRSV in this study was particularly high.Although it was not possible to distinguish between the classical porcine blue-ear virus,the highly pathogenic blue-ear virus,or the mutated NADC-30 virus,the existence rate of PRRSV was an indisputable fact,and measures such as purification should be taken to eliminate the disease.The positive rate was different in different pig farms.The pathogen detection rate was the lowest in breeding farms and higher in self-employed farmers.In nanyang CSFV,PRRS in 3 years antibody positive rate has degressive tendency,etiology detection has increasing trend,pig should further immunization work and must complete biological safety prevention and control measures to strengthen the disease prevention and control work,such as swine fever and often on the immune effect monitoring,adjust the number of immune and vaccine dose,eliminate positive pigs.This study lays a foundation for the comprehensive prevention and control of pig diseases in animal husbandry and veterinary supervision departments,and has guiding significance for the prevention and control of pig diseases in farmers.