Epidemiological Survey on the Main Pathogens of Porcine Respiratory Disease Complex in Yunnan Province

PurposePorcine respiratory disease complex (PRDC) is one of the important causes of economic losses of pig farms. The objective of this study was to investigate the mixed infection status and the main causative pathogens of porcine respiratory disease complex (PRDC) in large-scale pig farms and free-range households in Yunnan Province from 2016 to 2017.

MethodPCR or RT-PCR methods were applied, to detect the seven major viral and bacterial pathogens (i.e., CSFV, PRRSV, PRV, PCV2, MH, APP and HPS).

ResultOf 406 samples, 359 were identified as positive, of which the detection rate was 88.42%. There existed single infection and co-infection in the positive samples in Yunnan Province, among which the highest positive rate was found for PCV2 as 59.00%, while the lowest positive rate was found for APP as 9.09%. The highest rate of double co-infections was found for PCV2+PRRSV as 9.19%, followed by CSFV+PRRSV, with the infection rate 4.46%. The lowest rate for double co-infection was found for PRRSV+PRV and PCV2+MH, shared the same rate of 0.56%. Furthermore, mixed infections with three or five pathogens was identified, among which the co-infection with PCV2+CSFV+PRRSV showed the highest infection rate as 2.51%, while the counterpart for PCV2+PRRSV+PRV was the lowest (0.28%). Infection with five pathogens, like CSFV+PRRSV+PCV2+APP+HPS, was rarely observed, with a rate as 0.28%. No quadruple co-infection was found.

ConclusionThe survey indicated that PRDC infections were widely prevalent in Yunnan of which the pathogens were complex. So, we propose that the detection of PRDC infections should be strengthened to promote the prevention and control for local swine diseases.