This is cross sectional study at St. Paul's Hospital, a tertiary academic teaching hospital. Subjects ages 19 or greater with quiescent ulcerative colitis present for routine elective surveillance endoscopy will be invited for the study.
At enrollment, subjects will be evaluated for clinical and endoscopic disease severity using Mayo score. To be eligible for the study, Mayo score must be \<2. Supplemental blood tests, diagnostic test to determine CMV status, physical examination for extra-intestinal manifestation of CMV and inflammatory bowel disease, and surveillance colonoscopy with colonic biopsy will be done.
Patients will be followed longitudinally. Patients will be contacted every three months via their preferred method (telephone or email) until disease flare (clinical partial Mayo Score \> 2) or one year from enrolment. Patients will be asked to contact study coordinator when they are experiencing UC flare.
