1 Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305; Medical Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304;
2 Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305;
3 Department of Obstetrics & Gynecology, Stanford University School of Medicine, Stanford, CA 94305;
4 Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305; Medical Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304; Department of Microbiology & Immunology, Stanford University School of Medicine, Stanford, CA 94305 [email protected].