1. Division of Infectious Diseases; Johns Hopkins University; Baltimore MD USA
2. University of Pittsburgh Medical Center; Pittsburgh PA USA
3. Centers for Disease Control and Prevention; Atlanta GA USA
4. University of Michigan Medical School and Veterans Affairs Ann Arbor Healthcare System; Ann Arbor MI USA
5. University of Pennsylvania; Philadelphia PA USA
6. Washington University School of Medicine; St. Louis MO USA
7. University of Toronto Medical Center; Toronto ON Canada
8. University of Queensland; Brisbane QLD Australia
9. University of Alabama at Birmingham; Birmingham AL USA