Age-specific Prevalence of Porcine Reproductive and Respiratory Syndrome Virus, Porcine Circovirus Type 2, and Mycoplasma hyopneumoniae in Korea Pig Farms

Porcine respiratory disease complex (PRDC) continues to be a significant economic problem to the swine industry. Porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), and Mycoplasma hyopneumoniae (MH) are considered to be the most important pathogens that cause PRDC. In this study, we investigated the prevalence of antibodies against PRRSV and MH in the serum of sows and piglets from 89 domestic commercial pig farms by ELISA, and the presence of viral nucleic acids of PRRSV, including North American and European PRRS, and PCV2 was also investigated in the serum of sows and piglets from 89 domestic commercial pig farms by real-time PCR. In case of PRRSV, 78.7% (70/89) of sows were positive for PRRSV antibody, and 96.6% (86/89) of piglets were positive for PRRSV antibody. For MH, 76.4% (68/89) of sows showed positive for MH antibody. In the PRRSV viral nucleic acid detection experiment, 36.0% (32/89) of sows were positive for PRRSV nucleic acids, and virus nucleic acid was detected in 83.1% (74/89) of piglets. In case of virus type, both North American and European types were detected. In case of PCV2, 15.7% (14/89) of sows were positive for PCV2 nucleic acids. Conclusively, PCV2, PRRSV, and MH were widely distributed in pig farms in Korea. These prevalence data related with PRDC provides clinical information for vaccination strategy and development for the control of PRDC.