Prevalence of Cytomegalovirus in Patients With Newly Diagnosed, Flare-Up, and Acute Severe Ulcerative Colitis.

backgroundCytomegalovirus (CMV) is a ubiquitous virus belonging to the human herpesvirus that can reactivate in immunosuppressed ulcerative colitis (UC) patients, leading to frequent relapses and acute severe colitis. In inflammatory bowel disease, CMV colitis is linked to higher mortality, morbidity, and healthcare costs. CMV immunohistochemistry (IHC) is far more sensitive than routine H&E staining and should be part of the evaluation of UC patients with severe exacerbations or steroid-refractory disease during standard-of-care medical or surgical treatment. Severe CMV infection can cause fulminant colitis, toxic megacolon, or perforation, requiring urgent surgery. Colonoscopic findings may include patchy erythema, exudates, edema, erosions, deep ulcers, and pseudo-tumors. Despite growing evidence of CMV reactivation in UC, no official prevalence data exist for Nepal.

objectivesPrimary aim was to determine the prevalence of cytomegalovirus infection in newly diagnosed, flare-up and acute severe UC, and secondary aim was to evaluate the colonoscopic findings in patients with cytomegalovirus infection superimposed with UC Materials and Methods: A cross-sectional observational study was conducted at a tertiary center in the central part of Nepal from August 2024 to August 2025, among a group of 39 UC patients who were either newly diagnosed, UC in flare, or patients presenting with acute severe UC. All patients underwent either a flexible sigmoidoscopy or colonoscopy, and biopsies were taken from the inflamed mucosa for evaluation using histopathology with H&E stain and immunohistochemistry (IHC) with the CCH2 and DDG9 antibodies as markers for CMV. Data on demographic and clinical characteristics, endoscopic grading with Mayo's severity score, and extent of disease, along with stool examination for infectious etiology, including Clostridioides difficile along with relevant history for possible risk factors for relapse, such as complementary drug use, recent antibiotic and nonsteroidal anti-inflammatory drugs (NSAIDs) use, and non-compliance to therapy along with history of recent travel before onset of symptoms were obtained. Statistical analysis was done using IBM SPSS Statistics for Windows, version 21 (IBM Corp, Armonk, NY, USA).

resultsThe prevalence of cytomegalovirus infection in ulcerative colitis was found in 4 of 39 UC patients (10.25%). It was most common in acute severe cases (2/7, 28.57%) and in flares (2/26, 7.69%), with no cases in newly diagnosed patients (0/6). Immunohistochemistry detected all four CMV colitis cases, while histopathology identified only one, indicating that IHC is more accurate than histology alone for diagnosis.

conclusionThis study suggests cytomegalovirus infection as an important risk factor for relapse in patients with UC and should be evaluated with immunohistochemistry along with a histopathological study.