1 Division of Infectious Diseases and International Health, Duke University School of Medicine, Durham, NC, USA.
2 Department of Medicine, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil; Molecular Biology Laboratory, Santa Casa de Misericordia de Porto Alegre, Porto Alegre, Brazil.
3 Department of Internal Medicine, Division of Infectious Diseases and the Department of Medical Microbiology and Immunology, University of California Davis Medical Center, Sacramento, CA 95817, USA. Electronic address: grthompson@ucdavis.edu.