1. Department of Medicine, Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, California;
2. California Institute for Medical Research, San Jose, California;
3. Department of Pathology, Veterans Administration Medical Center, Palo Alto, California;
4. Department of Pathology, Stanford University, Stanford, California;
5. Centro de Pesquisas René Rachou, Fiocruz, Belo Horizonte, Brazil