Epidemiological Investigations Of Porcine Reproductive And Respiratory Syndrome (2013-2014) In Parts Of Sichuan Province

Porcine reproductive and respiratory syndrome (PRRS) has been a history in our pig breeding industry for a long time,it mainly cause reproductive disturbance of sow and respiratory system syndrome of piglets as the main features, the transmission speed is so fast and the spread range is also wide, and the development of China’s pig breeding industry is seriously affected. PPRS first broke out in our country in 1995, now the highly pathogenic PRRS disease is in the epidemic all over the province,it is more harmful compared to the classic PRRS disease. In order to timely and effectively understand the information on prevalence and infection of PRRS, RT-PCR method detecting antigen and ELIS A method detecting antibody have been frequently used in the laboratory.This paper detected 178 clinical samples of piglets, nursery pigs,growing pigs and fattening pigs by RT-PCR method from June 2013 to June 2014 in 7 citiesof Sichuan province including Chengdu Meishan、Suining、Leshan、Mianyang、Deyang、 Yaan, to understand the PRRSV infection, and compare the PRRSV infection from the cities above, different growth stages, different quarters, to investigate the prevalence of highly pathogenic PRRSV and classic PRRSV,and the mixed infection of PRRSV,CSFV, PRVandPCV2. The results showed that the highest positive rate of PRRSV was in Suining, it reached to 55.55%, the lowest positive rate is appeared in Mianyang, the positive rate is 27.27%. The positive rate is rising from a week of age to six weeks of age,and is declining from 7 weeks of age to 12 weeks of age.The high incidence of PRRSV is appeared in the third quarter (July to September); PRRSV infection is showed a growing trend from year 2013 to 2014 in Sichuan Province. In the 178 samples, The infection of highly pathogenic PRRSV is 55 cases in total and accounts for 38.76%;infection of classic PRRSV is 14 cases, the proportion is 7.25%.The mixed infection of PRRSV with CSFV, PRV and PCV2 account for 9.55%、2.81% and 20.79%。respectively.The study is also taken use of ELIS A to detect the blood samples of the PRRS vaccine immunized fattening pigs (7-10 weeks of age), gilts, sows of the maternity ward, breeding boars,a total of 5053 copies from June 2013 to June 2014 in eight cities of Sichuan province including Chengdu、Meisha、Suining、Leshan、Mianyang、 Deyang、Nanchong、Yaan. Standing, centrifugating the fresh blood samples collected, conserving the serum at 4℃ for use. It Used HerdChek antibody detection kit of porcine reproductive and obstacles syndrome virus studied by IDEXX company to detect all of the PRRSV serum antibody levels of four swinery. Using EXCEL software and data analysis software to analyze data and calculate the average, S/P ratio, coefficient of variation. The results showed that:the average positive rate of PRRS antibody and the average passing rate of fattening pigs is the lowest (7-10 weeks of age) it is 68.9%and55.5%,, then gilts is 73% and 77%, respectively and then sow of the delivery room is 78.9% and 73.0%, respectively,the highest is breeding boars, it is 78.8% and 74.5%, respectively.Coefficient of variation of the antibody levels in 4 swinery are all less than 30%. Effect of Immunization is the best Chengdu, Effect of immunization is the worst in Meishan and Nanchong.From the epidemiological investigation for the suspicious pig farms of porcine reproductive and respiratory syndrome infection from year 2013 to 2014 in Sichuan multiple regions farms,it can be concluded that a variety of day-old pigs can be infected with the disease all year round, and HP-PRRSV has higher incidence rates, and gradually replaced the classic PRRSV dominance. All of the collected clinical samples of PRRSV, CSFV, PRV, PCV2 antigen detection show it began to shift from a single incidence of infectious diseases outbreak to hybrid disease. The result of serum survey showed the positive rate of PRRS in Sichuan province is generally higher than the requirements of 70% published by Ministry of Agriculture, on the whole, Regionally, PRRS antibody positive rates in Chengdu and Mianyang are the highest, antibody positive rate and PRRS antibody passing rates are the lowest in Nanchong and Ya’an region, and the coefficient of variation are maximum, there is a potential threat to the outbreak of PRRSV, which should attract local farms’attention.