202 FOODBORNE PATHOGENS AND DISEASE Volume 1, Number 4, 2004 © Mary Ann Liebert, Inc. Review The Role of Contaminated Feed in the Epidemiology and Control of Salmonella enterica in Pork Production PETER R. DAVIES, 1 H. SCOTT HURD, 2 JULIE A. FUNK, 3 PAULA J. FEDORKA-CRAY, 4 and FRANK T. JONES 5 ABSTRACT Food animal producers have ethical obligations to reduce the risk of foodborne hazards in animals under their care. Contaminated feed is a recognized source of Salmonella infection of food animals and regulations to control Salmonella contamination of animal feed have existed in some countries for decades. The impact of reducing Sal- monella contamination of animal feeds on the risk of human foodborne salmonellosis is difficult to assess, and is likely to vary among food animal industries. In the context of U.S. pork production, factors that may attenuate or negate the impact (on public health) of regulatory interventions to control Salmonella in commercial feed in- clude widespread use of on-farm mixing of swine feed; incomplete decontamination of feed during processing; post-processing contamination of feed at feed mills or in transportation or on-farm storage; the multitude of non- feed sources of Salmonella infection; an apparently high risk of post-farm infection in lairage; and post-harvest sources of contamination. A structured survey of the extent of Salmonella contamination of animal feed in the United States is necessary to enable more informed debate on the feasibility and likely efficacy of enforcing a Salmonella negative standard for animal feeds to reduce the incidence of human salmonellosis. INTRODUCTION F OOD SAFETY is critical to consumer confi- dence in the food supply and the prosper- ity of food producing enterprises. For meat industries, the 1990s brought revolutionary changes in both regulations and consumer at- titudes towards food safety which drew atten- tion to the responsibilities of the animal pro- duction sector to reduce the risk of foodborne illness. The “farm-to-table” concept (where all participants in food production and consump- tion bear responsibilities for reducing the risk of foodborne disease) is now the accepted par- adigm for addressing food safety. However, for many hazards, meaningful analysis of how the farm-to-table paradigm should be realized is lacking. Conceptually, we can view the food supply continuum as a linear series of sectors engaged in production, harvest, distribution, and consumption. Within any sector measures can be applied to reduce risk of foodborne haz- ards, and the goal is to define the optimal mix of interventions across the continuum that de- 1 Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota. 2 Pre-Harvest Food Safety and Enteric Diseases Research Unit, National Animal Disease Center, Ames, Iowa. 3 Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Colum- bus, Ohio. 4 USDA Agricultural Research Service, Russell research Station, Athens, Georgia. 5 Center of Excellence for Poultry Science, University of Arkansas, Fayetteville, Arkansas.