1. Department of Nutrition and Food Science, University of Maryland, College Park, Maryland.
2. Environmental Microbial and Food Safety Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland.
3. Center of Food Safety and Security Systems, University of Maryland, College Park, Maryland.
4. Bureau of Animal Health and Diagnostic Services, Pennsylvania Department of Agriculture, Harrisburg, Pennsylvania.
5. Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania.
6. Statistic Group, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland.