Abstract: To understand the recent prevalence of several viral diseases in sick pig farms, 147 tissue specimens were collected from 50 farms in 11 provinces (cities) and examined during January 2010 to May 2010 by RT-PCR and PCR methods. And 458 serum samples from 26 farms were examined for pseudorabies gE antibodies by ELISA method. The positive rate of porcine circovirus type 2 (PCV2) was highest with 75.3% (70/93). The positive rate of porcine reproductive and respiratory syndrome virus (PRRSV) followed with 57.4% (78/136), and that of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) was 43.5% (54/124). The positive rates of classical swine fever virus (CSFV) and pseudorabies virus (PRV) were 37.7% (52/138) and 21.0% (21/100), respectively. The positive rate of pseudorabies gE antibody was 16.4% (75/458). 46.9% (69/147) of samples including two and more than two species pathogens were detected, and HP-PRRSV+PCV2, CSFV+PCV2, and CSFV+HP-PRRSV+PCV2 were three forms of the most common. PRRSV (50.0%) was the most common cause of pig reproductive disorders; CSFV (56.0%) and PCV2 (48.0%) were the common causes of diarrhea in the pre /post-weaning; HP-PRRSV (53.5%), CSFV (50.7%) and PCV2 (48.0%) were commonly detected in nursery pigs with high fever syndrome. The results provided references for the diagnosis, prevention and control of swine diseases.

Key words: CSF; PRRS; PR; PCV; PCR; ELISA; detection