| Porcine circovirus type 2(PCV2)is a kind of pathogen which can inhibit host immunity seriously. The incidence of the disease is spreading gradually accelerate, it has brought pressure to the global pig industry, and related researchers in the field say the disease is a new serious infectious disease after PRRS(Porcine Reproductive and Respiratory Syndrome).In the early 1990 s, due to the severe negative impacts of PCV2 on the pig farming industry, scholars from North America and West Europe initiated investigations on the epidemiology of PCV2. Starting from year 2000, Hong Wu Lang and other epidemiologists began to investigate PCV2 in some pig herds in North China. The results show the certainty of the existence and prevalence of PCV2 in China. Due to the fact that swine-herd industry in Shanghai has a great circulation pattern, and the geographical proximity between Qing Pu District of Shanghai and large swine heard industry provinces such as Jiangsu and Zhejiang, it is necessary and beneficial to perform a systemic investigation on PCV2 infestation in Qing Pu area.In this paper,we conducted a serological investigation of seven swineherd in Qing Pu area during a period of October 2011 to May 2013. The results of the study include the following points:The enzyme-linked immune sorbent assay(ELISA) was used to detect PCV2 anti-body levels in 3463 serum samples from pig herds. The results showed that PCV2 infection in the six non-immunized-swineherds. A total of 2973 samples from non-immunized-swineherd, total antibody positive rate was 37.10%(1103/2973), in which October 2011 sample showed 24.22%(179/739) positive rate, May 2012 sample showed 35.75%(270/755) positive rate, October 2012 sample showed 42.80%(321/750) positive rate and May 2013 sample showed 45.68%(333/729) positive rate?PCR assay was used to detect PCV2 virus in 3464 serum samples. The results showed that positive rate of PCV2 in non-immunized-swineherd is much higher than that in immunized-swineherd and PCV2 infection existed in all tested pig farms. Among the total 2974 samples, from non-immunized-pig farms, the total positive rate was 18.04%(625/2974), in which October 2011 sample showed 10.41%(77/740) positive rate, the May 2012 sample showed 16.56%(125/755) infection rate, the October 2012 sample showed 22.67%(170/750) infection rate, and the May 2013 sample showed 30.59%(223/729)?490 serum samples collected from the NO.7 immunized swineherd were analyzed for PCV2 virus and the antibody levels. The results showed that the antibody positive rate was 73.67% 361/490), which is higher than that of the other six non-immunized-swineherd significantly, and the PCR positive rate was 6.12%(30/490) which is lower significantly.In order to investigate PCV2 infection of different age groups of study subjects, serum samples were collected from subjects divided into 5 different age groups including weaning piglets, replacement gilts, fattening pigs, sows and boars, respectively. Difference between the age and the positive rate, the rate from low to high in order is: replacement gilt(23.15%),fattening pigs(39.76%),weaning piglets(40.27%),multi-parity sows(44.75%) and boar(46.88%).In summary, these data implied that PCV2 infection is very popular in swine herds in Qing Pu area, and the PCV2 vaccine was suggested to be immunized to control the PCV2 infection. |
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