1. Department of Microbiology and Immunology, The University of Iowa, Iowa City, Iowa, United States
2. Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, Iowa, United States
3. Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, United States
4. State Hygienic Laboratory, The University of Iowa, Iowa City, Iowa, United States
5. Department of Pathology, University of Iowa Hospitals & Clinics, Iowa City, Iowa, United States
6. Department of Biostatistics, School of Public Health, The University of Iowa, Iowa City, Iowa, United States