Abstract
A survey was performed on antibody against Haemophilus equigenitalis in 4 312 mare sera collected in Japan over a period from 1975 to 1980 by using the complement fixation (CF) test with a simple washing culture of the organism as an antigen. Every year since 1978 CF antibody was detected from broodmares in Hokkaido, the northern part of Japan, where contagious equine metritis (CEM) was first diagnosed in 1980. It was also detected from 3 of 454 serum samples collected before covering in 1978. It was likely that CEM might have been introduced into Japan prior to 1978. CF antibody was detected from 20.9% of sera randomly collected from broodmares in the breeding region within 2 months after covering in 1980, but not from any racehorses or fillies during a period from 1975 to 1980. It was assumed that the organism might be widespread among broodmares in the breeding region, but not among racehorses or rearing horses.
