Investigation Of Epidemiology Of Porcine Circoviruses In JinHua Of ZheJiang Province

Porcine circovirus disease(PCVD)originated by Porcine circovirus(PCV) is a multisystem functinal disturbance disease, and lead to immune suppression. The affected pigs have a variety of clinical signs, including progressive emaciation, asthma, dyspnea, pallor of the skin or icterus, palpable lymph node enlargement and hepatic cirrhosis at necropsy.Except for post-weaning multisystemic wasting syndrome(PMWS), porcine circovirus was also identified in pigs with various other disease syndromes, such as porcine dermatitis and nephropathy syndrome(PDNS), porcine respiratory disease complex(PRDC), congenital tremor (CT) in newborn pigs or reproductive disorders. For the occurrence and outbreak of these disease syndrome cause widespread significant economic losses, currently, Porcine circovirus is generally considered to be an important emerging porcine infectious diseases after Porcine Reproductive and Respiratory Syndrome (PRRS) was reported, and present a threat to our swine industry.Many research data shows that PCV2 often has an mixed infection of pigs withporcine reproductive and respiratory syndrome virus (PRRSV), porcine parvovirus (PPV), porcine pseudorabies virus (PRV), etc. And sometimes the disease is subclinical infection. But so far very superficial understanding of PCV2, it was not aware of the immune mechanism and pathogenesis, and there is no effective vaccine for the disease prevention and control, and we can not develop practical and effective disease prevention and control measures. Therefore further studies about PCV are needed in epidemiology, molecular biology and immune mechanisms, etc, in order to ultimately control the PCV infection. In this paper, we conducted a serological and etiological investigation in 8 counties (cities, districts) of JinHua during a period of March 2008 to October 2009. The experimental results are as follows:A total of 934 samples collected from 31 pig farms were detected by an enzyme-linked immunosorbent assay. The results showed that in JinHua almost all swine herds, PCV2 infection was common, all the pig farms tested existed in PCV2 infection and antibodies positive rate were 100%.In the 934 serum samples, seroprevalence of antibodies to PCV2 was 63.38%(592/934), of which WuCheng District 75.61%(214/283), Lanxi City 71.07% (86/121), Yiwu City 63.73%(116/182), and the positive rate of these three cities were higher than the average. Judging from the incidence, PCV2 in our region, there are still a certain proportion of latent infection.According to the source of serum under investigation were from pigs of all ages, we divided the pigs into five age groups,not weaned piglets, weaned piglets, fattening pigs, replacement gilt and multiparity sows. The results show that, positive rates of PCV2 infection have some correlation with age, from low to high were as follows:not weaned piglets(51.21%), weaned piglets(56.76%), fattening pigs(64.23%), replacement gilt(70.74%) and multiparity sows(76.29%).The collected 192 samples suspected for PCV2 infection symptoms was detected by polymerase chain reaction(PCR). The results indicated that the total average positive rate was 59.80%(61/102). In which, to pathogen detection, the positive rate was found in 69.09%(38/55) of the 55 samples with clinical symptoms of suspected PMWS, and in 45.00%(9/20) of the 20 sample with clinical symptoms of suspected PDNS, and in 51.85% (14/27) of the 27 samples with the clinical symptoms of reproductive barriers.The 61 PCV2-positive samples were detected respectively using PCR diagnostic methods, for swine fever, porcine reproductive and respiratory syndrome, as well as the detection of porcine parvovirus. The results showed that a larger proportion of mixed infection, accounting for 80.33%(49/61) of the positive samples, and in which PCV2 and PRRSV were the largest mixed double infection, taking up 34.43%(21/61), triple infection with PCV2, PRRSV and PRV were 11.47%(7/61). It revealed the state of PCV2 infection, prevalence of law and mixed infection in our region, and lay the foundation for effectively prevent and control the diseases infected by PCV2.