1. 1Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742
2. 2Center for Food Safety and Security Systems, University of Maryland, College Park, Maryland 20742
3. 3U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agriculture Research Center, Animal Parasitic Diseases Laboratory, Beltsville, Maryland 20705
4. 4National Academy of Sciences, Washington, DC 20001, USA