Investigation of porcine circovirus type 2 infection in mainland China

In order to understand porcine circovirus type 2(PCV2) infection in Chinese pig population and analyze the relationship between the PCV2 infection and pig age,a total of 2 905 serum samples were detected for PCV2 by PCR method,which were collected from 71 small to medium scale farms,22 slaughter houses and 62 backyard farms in 28 provinces of mainland China in 2009.The results showed that 429 positive serum samples were found,and the average positive rate was 14.8%.The positive farm rate of slaughter houses,scale farms and backyard farms were 86.4%,52.1% and 58.1%,respectively,and the infection rate of 48.6% positive scale farms was less than 10%.To analyze the correlation between the PCV2 infection and pig age,the pigs of scale farms were divided into five age groups.The results showed that PCV2 infection was not detected in 2-4 week group,but in all other groups.The positive rate of 11-14 weeks group and 15-26 weeks group was higher than 5-7 weeks group and 8-10 weeks group.This work investigated the PCV2 infection in most Chinese provinces and explored the relationship between the PCV2 infection and pig age,and it provided valuable data for controlling the possible risk of PCV2 infection for the Chinese pig industry.