Epidemiology of Salmonella contamination of milk on a commercial dry-lot dairy

摘要

The propensity for Salmonella to contaminate milk has been recognized for many years however the epidemiology of Salmonella contamination of milk has not been defined. There are numerous reports of human salmonellosis linked to contaminated milk andSalmonella contamination of milk and colostrum represents a direct mechanism of disease transmission from cows to calves. Possible origins of Salmonella in bulk tank milk include Salmonella infected mammary glands and fecal contamination during milking.There is a paucity of studies documenting the frequency of intra-mammary Salmonella infections in cattle, however, cows with chronic Salmonella infections have been observed to shed Salmonella in milk as well as feces. The bovine mammary gland may be infected hematogenously or via intra-mammary inoculation. Chronic Salmonella infections are most commonly associated with S. dublin but have also been reported to occur with S. typhimurium (B), S. Ohio (C), S. enteritidis (D), and S. muenster (E). The objective of the present study was to determine the frequency of Salmonella shedding in milk by cattle on a farm endemically infected with Salmonella and to identify risk factors for intra-mammary Salmonella infections and Salmonella contamination of bulk tank milk.