关键词: 猪；胞内劳森菌； 巢式PCR； ELISA； 流行病学

Abstract: In order to provide evidence for precise prevention and control of Porcine proliferative enteropathy， the prevalence of Lawson Intracellularis in large?scale pig farms under the background of antibiotic?free feed and restricting the use of antibiotics in pig breeding industry was investigated. In this study，nested PCR and indirectELISA were used to detect fecal and serum samples from different pig farms. Under the background of antibiotic?free feed，nested PCR detection was conducted on 695 fecal samples collected from different pig farms. the overall infection rate was 23.88%. The infection rates of nursery pigs，finishing pigs and boars were 16.56%，29.58% and 24.63%，respectively. The results of the follow?up survey of the pig herds with antibiotic?free feed and under the background of restricting the use of antibiotics in pig breeding industry were as follows：the infection rate of nursery pigs at 30，44，58 and 72 days of age was 16.67%，20.00%，50.00% and 70.00%，respectively. The infection rate of gilts ranged from 44.44% to 66.67%. As for the ELISA test results，the positive rate of lawsonia intracellularis was 42.6% in 338 serum samples and the positive rate of Lawsonia Intracellularis range from 10% to 75.90% in pig farms from different provinces. The aboved results showed that the prevalence of Lawsonia Intracellulare in large?scale pig farms in China were at a high level at present. The highest infection rates of nursery pigs and gilts were 70% and 66.67% respectively. The infection rate of nursery pigs increased significantly with the increase of age. Therefore，it is necessary to pay more attention to the prevention and control of porcine proliferative enteropathy in large?scale pig farms under the background of antibiotic?free feed.

Key words: Pigs； Lawsonia Intracellularis； Nested PCR； ELISA； Epidemiology