Vaccine and epidemiologic studies of Salmonella infections in swine
Four vaccine studies were conducted. The first vaccine study determined that pigs vaccinated with SC54TM at one day of age were protected at 35 days of age against infection by S. choleraesuis. Vaccine studies two and three determined that SC54TM was not effective in protecting pigs against challenge by S. typhimurium. The fourth vaccine study was an investigation of the association of SC54TM use and the reduction of the bacteriologic and serologic prevalence of Salmonella in a commercial herd. Results from this vaccine study suggested that vaccination of pigs with SC54TM reduced the bacteriologic prevalence of some Salmonella serogroups. The results from this fourth study also suggest that SC54TM may reduce the seroprevalence of Salmonella in pigs at the time of slaughter;Samples of serum and feces from pigs were collected for most of one year from three farms. In addition, mesenteric lymph nodes and meat juice samples were collected from pigs from the same farms at slaughter. The results from these studies suggested that groups of pigs with high levels of Salmonella detected by culture also have high levels of antibody to Salmonella as measured by the mix-ELISA;A serologic survey of samples from several farms throughout the Midwest was conducted to detect the presence of antibody to Salmonella. A questionnaire was completed by some farms. Pig performance data was made available for some groups of pigs, also. The results from these studies suggested that a decrease in the seroprevalence of Salmonella associated with the use of an isolated nursery and with testing of pigs during the first two quarters of the year. It was also shown that there was an association between management factors recorded at the time of pig placement and an increased seroprevalence of Salmonella. Finally, low growth performance based upon the pounds of pork produced (liveweight) per square foot of building per year was associated with groups of pigs that had high levels of Salmonella;In addition, some serum samples were tested for the presence of antibody to Toxoplasma gondii, Trichinella spiralis, and Yersinia enterocolitica O:3. The prevalence of T. gondii and T. spiralis antibodies was below 0.01. There was a direct association between the seroprevalence of Y. enterocolitica O:3 and the seroprevalence of Salmonella.