Co-infection with S. choleraesuis and porcine reproductive and respiratory syndrom (PRRS) virus
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The SafePork conference series began in 1996 to bring together international researchers, industry, and government agencies to discuss current Salmonella research and identify research needs pertaining to both pig and pork production. In subsequent years topics of research presented at these conferences expanded to include other chemical and biological hazards to pig and pork production.
Porcine reproductive and respiratory syndrome virus (PRRSV) and Salmonella choleraesuis (SC) are important components of the swine respiratory disease complex. Although respiratory disease is a major clinical component of PRRS in field cases, it has been difficult to produce respiratory disease in pigs in the research environment simply by exposure to PRRSV. It has been postulated that this may be due to low pig density, ideal housing conditions, and the absence of concurrent bacterial infections in the research setting. Pigs subclinically infected with SC are considered the most common source of infection to naive herds. Like PRRS, it is not clear why and how subclinical infections are triggered to become acute outbreaks of disease. It has been suggested that a variety of stressors, including the presence of concurrent viral infections, may lead to clinical outbreaks of salmonellosis. On two Midwestern farms, nursery mortality due to salmonellosis reportedly increased following herd outbreaks of PRRS. This led the authors to suggest that concurrent PRRSV infection may serve to provoke clinical salmonellosis. The work reported here was intended to explore these issues. Specifically, our objective was to investigate the interactive effects of exposure to PRRSV, SC, and stress on growth performance and disease in young swine.