| Porcine epidemic diarrhea(PED)is a kind of acute and highly infectious intestinal disease caused by porcine epidemic diarrhea virus(PEDV),which is characterized by diarrhea,vomiting,dehydration and even death.The high mortality rate of suckling piglets is a typical feature of this disease.The mortality rate can reach 50%～100%.It is an important disease that endangers the pig industry.Vaccination is the main way to prevent and control the disease.In China,the inactivated vaccine or attenuated vaccine prepared by PEDV CV777 strain has achieved good results.However,since the winter of 2010,there has been a variant strain of swine diarrhea,which leads to the unsatisfactory immune effect of PEDV CV777 vaccine which can not provide a good protection for the immunized pigs.As a result,the disease broke out in a large range in China,the United States,South Korea and other countries,resulting in the death of millions of suckling pigs and huge economic losses.In order to understand the prevalence of epidemic diarrhea in Fuyuan,Heilongjiang Province,in this study,questionnaire survey,antibody positive rate and antigen detection rate were used.the large-scale pig farms and scattered households in this area were investgated and the immune effects of different types of adjuvant vaccines with different ways of vaccination were studied,and then the reference for the prevention and control of epidemic epidemic diarrhea were provied for the different farmers in this area.During the period from September 2018 to September 2019,A survey of epidemic diarrhea was carried out among 136 large-scale pig farms and scattered farmers in Fuyuan Town,Nongqiao Town,Zhuaji Town,bielahong Town,Haiqing Town,Yanan Town,Nongjiang Town,Tongjiang town and Hanconggou town,At the same time,the data of pig groups(suckling piglets,nursery pigs,fattening pigs,reserve sows and breeding pigs)in different growth stages were collected.Among the large-scale pig farms,a total of 17 samples were distributed and 16 were recovered,with a recovery rate of 94.12%.Among the scattered farmers,a total of 136 samples were distributed and 127 samples were recovered,with a recovery rate of 93.38%.According to the results of this survey,during this period,there were 6 farms with clinical diagnosis of PEDV,accounting for 5.96%of the total number of investigations.It shows that there is an epidemic of epidemic diarrhea in Fuyuan.According to different growing stages of pigs,different seasons and different breeding methods,the antigen detection rate and antibody level of the collected disease materials and serum were statistically analyzed.The results indicated that the highest antigen detection rate and the lowest antibody positive level were found in suckling piglets.With the increase of pig age,the antigen detection rate gradually decreased and the antibody positive level gradually increased.In the adult pig stage(including the back sows and sows),the antigen detection rate was the lowest and the antibody positive level was the highest.The detection rate of pathogens was higher in winter and spring,and the antibody level of swine was lower.In summer and autumn,the detection rate of pathogens is low,and the antibody level of pigs is high,Swine epidemic diarrhea was more likely to occur in winter and spring.No matter in antigen detection rate or antibody positive level,large-scale farms were better than those of scattered farmers,so more attention should be paid to the prevention and control of epidemic diarrhea in scattered households.Compare the immune effects of different vaccination routes with the changes in serum antibody levels of piglets and sows immunized with vaccines and the detection of IgA antibody level in postpartum sow milk,It was found that the immune effect of pigs inoculated with water adjuvant vaccine is slightly better than that of pigs inoculated with aluminum hydroxide glue adjuvant vaccine,Therefore,the water adjuvant vaccine should be the first choice in the choice of vaccine types.During this investigation,the control effect of inactivated vaccines with different adjuvants for swine epidemic diarrhea was investigated,the results indicated that during this period,the antibody positive rate of serum samples collected from pig farms inoculated with the vaccine was more than 80%,and the detection rate of PEDV in tissues,feces and other samples was less than 6%,which indicated that it had a good immune effect on PEDV.The importance of vaccination can also be seen from the fact that the antibody positive rate of the collected samples is less than 20%and the detection rate of PEDV of the collected tissues,feces and other samples is more than 9%.In addition,no matter in large-scale pig farms or in scattered breeding households,although there is a good antibody positive rate for the aluminum adjuvant vaccine prepared by classical strains,the antigen detection rate is significantly higher than that of the pigs inoculated by mutated strains.Therefore,it can be concluded that there are variant strains of PEDV in Fuyuan city. |
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