1. Department of Pediatrics, University of California, Irvine, Irvine, California, Division of Pediatric Infectious Diseases, Memorial Miller Children's Hospital, 2801 Atlantic Avenue, Long Beach, CA 90801-1428
2. Jefferson Medical College, Philadelphia, Pennsylvania
3. Department of Pediatrics, University of California, Irvine, Irvine, California, Memorial Miller Children's Hospital, Long Beach, California