Epidemiological Investigation Of Porcine Reproductive And Respiratory Syndrome In Guangxi

Porcine reproductive and respiratory syndrome (PRRS) is a viral disease of domestic swine characterized by pregnant sow reproductive failure, dyspnea, high mortality in piglets and respiratory signs in growing pigs. In the present study, 392 tissue samples of field cases originated from 38 pig farms suspect of 14 cities in Guangxi province were detected by reverse transcription polymerase chain reaction (RT-PCR) between January and July in 2004. Indirect enzyme-linked immunosorbent assay (ELISA) was also used to monitor the antibody against PRRSV of 1130 serum samples from non-vaccinated herds without clinical signs of 47 farms in Guangxi.The results of RT-PCR showed that 68.4% (26/38) of the pig farms gave positive tests, scattered all of 14 regions. The average positive rate of PRRSV in samples was 28.6% (138/392) with the maximal positive rate of 53.6% and the minimum of 8.1% . The results of detection of sera indicated that the average rate of indirect ELISA-positive was 31.3%(354/1130), with the highest positive rate of 48.7% and the lowest of 13.1 %.The results of the epidemiological investigation demonstrated that PRRS was prevalent in Guangxi, however, its positive rate is different in various regions. The positive rate in the regions with many and small-scale pig farms was relative high. Additionally, the morbidity and mortality of PRRSV infection vary greatly in herds of variant stage, with the highest mortality in the neonatal pigs. No significant difference was noted in the susceptibility to the virus and positive rate in different varieties.