Prevalence and Infection Status of Salmonella in 25 Conventional Swine Farms in Korea

The aim of this study was to determine the prevalence and infection status of Salmonella species (spp.) in 25 conventional pig farms by traditional fecal culture and serological methods to develop a Salmonella control program for Korean pig farms. The individual seroprevalence of Salmonella spp. in pigs reared in the 25 pig farms was 83.1% in sows and 6.4-32% in different aged pig groups, with the total seroprevalence 28.4% (141/848). The seroprevalence of the tested pigs increased in accordance with the decrease in maternal antibody and the rearing period on these farms. Of note, all the 25 pig farms contained at least two or more anti-Salmonella antibody-positive sows. In the fecal cultures Salmonella spp. were isolated only in three (12.0%, 3/25) of 16 serologically Salmonella-suspected farms (64.0%, 16/25), showing the limitation of the fecal culture method and the need for serum assays to understand the exact status of Salmonella infection in swine herds, which likely contain subclinically infected pigs or carriers. The results highlight the need to establish a supply system of Salmonella-free gilts for the promotion of a national Salmonella control program on swine farms in Korea. Further studies will be needed to develop an effective monitoring system for the implementation of a national Salmonella control program.