1. Division of Human Biology; Fred Hutchinson Cancer Research Center; Seattle WA USA
2. National Cancer Institute; NIH; Rockville MD USA
3. Proyecto Epidemiológico Guanacaste; Fundación INCIENSA; Guanacaste Costa Rica
4. International Agency for Research on Cancer; Lyon France
5. Clinical Microbiology Laboratory; Harborview Medical Center; Seattle WA USA
6. Department of Laboratory Medicine; University of Washington; Seattle WA USA
7. Department of Microbiology; University of Washington; Seattle WA USA