1. Virginia Commonwealth University Medical Center, Richmond, Virginia, USA
2. Cleveland Clinic, Cleveland, Ohio, USA
3. University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
4. Southern California Permanente Medical Group, North Hollywood, California, USA
5. Florida Department of Health, Bureau of Public Health Laboratories, Jacksonville, Florida, USA
6. National Jewish Health, Denver, Colorado, USA
7. Skaraborg Hospital, Skövde, Sweden
8. Wisconsin State Laboratory of Hygiene, Madison, Wisconsin, USA
9. Denver Health, Denver, Colorado, USA