1. Division of Infectious Diseases; Washington University School of Medicine; St. Louis MO USA
2. Centers for Disease Control and Prevention; Atlanta GA USA
3. Division of Infectious Diseases; University of Pittsburgh; Pittsburgh PA USA
4. University of Pennsylvania; Philadelphia PA USA
5. VA Ann Arbor Healthcare System; University of Michigan Medical School; Ann Arbor MI USA
6. Johns Hopkins University; Baltimore MD USA
7. University of Alabama at Birmingham; Birmingham AL USA