Investigation of seroepidemiology of Mycoplasma hyopneumoniae infection and establishment of on-farm eradication protocol

Seok, Ho-bong; Joo, Han-soo

Korean Journal of Veterinary Research 1999;39(6):1218-1223.

Ho-bong Seok¹, Han-soo Joo²

¹Department of Animal Science, Dankook University
²Department of Clinical and Population Science, Minnesota University

Mycoplasma hyopneumoniae 감염의 혈청역학적조사 및 농장에서의 근절방안 설정

석호봉¹, 주한수²

¹단국대학교 동물자원학과
²미네소타대학교 수의과대학

Abstract

The purposes of this study are to examine seroprevalence of Mycoplasma hyopneumoniae infection in pigs of different age groups, and retrospectively determine if nursery depopulation (ND) could influence the seroprevalence of M hyopneumoniae infection in nurseries. Sera of 4, 8, 12, 16, and 20 weeks old pigs from 7 farms were first selected from a serum bank to examine serologic profiles for M hyopneumoniae infections. Availability of representative sera in the serum bank was a major criterion for farm selection. The sera were tested for M hyopneumoniae antibodies by an enzyme linked immunosorbent assay (ELISA) using Tween-20 extracted antigen. Serum samples were also selected from 15 of 34 swine farms that previously participated in a ND study. In order to evaluate M hyopneumoniae infection following ND, ELISA was performed with sera of 8~10 weeks old nursery pigs collected prior to and after ND for up to 12 months from the 15 farms. Serological profiles showed positive ELISA titers for 2 of 7 farms at 8 weeks, 4 of 7 farms at 12 weeks, 6 of 7 farms at 16 weeks, 6 of 6 farms at 20 weeks of age. Prior to ND, 11 of the 15 farms had positive titers in sera of 8~10 weeks old pigs. Sera of 8~10 weeks old pigs collected from 7 of the 11 farms (63.6%) were ELISA antibody negative for up to 12 months following ND. In conclusion, seroconversion to M hyopneumoniae was detected commonly between 10~16 weeks of age, indicating the occurrence of natural infection during the nursery age. The ND appeared to be an effective method to prevent M hyopneumoniae infection within the nursery pig in some farms.

Key Words: Mycoplasma hyopneumoniae, seroepidemiology, nursery pig, eradication protocol