Prevention of salmonellosis in dairy cattle

摘要

Exposure of cattle to Salmonella can result in a wide spectrum of sequelae ranging from subclinical infection to enteritis, abortion, bacteremia/septicemia and death. Salmonella typhimurium, S. dublin, S. kentucky, S. montevideo, S. newport, S. anatum, and S. muenster are the most common Salmonella serotypes isolated from cattle in the United States. Variables that appear to affect the outcome of the host-pathogen interaction include the immunity of the host, dose and virulence of the pathogen (serotype), and environmental and management factors that affect the level of exposure to pathogens. The most common epidemic infections are associated with S. typhimurium (group B), and other group B, C, and E Salmonella. Cattle that recover from infectionswith these serotypes usually cease shedding Salmonellae in feces within 3 to 12 weeks and rarely become chronic carriers. Although cattle infected with these serotypes do not usually become chronically infected, herd infections may be persistent, presumably due to heavy environmental contamination and recycling of Salmonellae between cows, feed, and the environment. In contrast, S dublin, the most common group D Salmonella to affect cattle does cause chronic infections in cattle and may be introduced and or maintained on farms by long term carrier cattle.