The Clinical Core has ultimate responsibility for recruiting patients and obtaining all patient-related specimens and data. Eligible patients are those referred for colonoscopy and upper endoscopy at the University of Maryland Medical Center (UMMC). Based on current patient volumes, we anticipate having approximately 8000 patients available for the study. The clinical core will be responsible for initial patient contact and patient enrollment, including obtaining appropriate written informed consent. They are responsible for coordinating the collection of blood and stool specimens, administration of vaccine, collecting demographic data, and collection of biopsy specimens during colonoscopy/upper endoscopy.