Seroprevalence of Leptospira spp. in clinically healthy racing horses in Korea.

Leptospirosis is a zoonotic disease of global importance, and has a worldwide distribution. The present study aimed to determine leptospiral seroprevalence in clinically healthy racing horses from all three racecourses in Korea. Serum samples from 1,226 racing horses were examined using a microscopic agglutination test to detect the presence of antibodies against 18 Leptospira serovars. Of the tested samples, 307 (25.0%) were found to be positive. The distribution of seroprevalence differed significantly by racecourse (P=0.004); the Jeju course had the highest incidence (31.1%), followed by the Seoul (25.2%) and Busan (19.5%) racecourses. Seasonal variation in seropositivity was also apparent (P=0.000), being lower in spring (13.0%) and winter (12.5%), and higher in summer (36.7%) and autumn (34.7%). No significant age- or gender-related difference in seroprevalence was noted in this study (P>0.05). Seroprevalence was higher (P=0.006) among ponies than among thoroughbreds. Sejroe was the most frequently detected serovar (n=236), followed by Bratislava (n=35), Ballum (n=16), Autumnalis (n=10), and Canicola (n=10). The majority of serum titers were relatively low; most values ranged from 1:100 (n=217) to 1:200 (n=69). These results suggest that the Sejroe serovar may be maintained in the racing horse population in Korea.