Abstract
Prevalence of the complement-fixation antibody againstMycoplasma hyopneumoniaewas determined in 18, 995 serum samples collected from sows and fattening pigs of various ages in Japan between 1995 and 1997. At least 1 pig in 504 (96.0%) of 525 conventional herds sampled had the minimal titer of 1: 4 againstM. hyopneumoniae. Of 18, 995 serum samples, 8, 324 (43.8%) demonstrated an antibody titer of 1: 4 or higher. The seropositive rate (titer≥1: 4) in fattening pigs was 20.1%(GM titer 1: 19.8) before the age of 1 month. After 1 month of age, it decreased. Thereafter the seropositive rates increased gradually to reach 63.9%(GM titer 1: 18.1) at 6 months of age. Seropositive rates in sows decreased with increasing numbers of farrowing. Little seasonal or regional difference in positive rates was observed. These results suggest thatM. hyopneumoniaeinfection is still widespread among pigs in Japan.
