Human Cytomegalovirus and Epstein–Barr Virus Infection in Inflammatory Bowel Disease: Crossing the Diagnostic Barrier for Appropriate Management

Human cytomegalovirus and Epstein-Barr virus are widely distributed viruses that, upon primary infection, establish a lifelong latency in immunocompetent subjects, whereas, in immunocompromised patients, they may give rise to secondary infection. In the latter case, either virus may cause systemic or end-organ disease that, if localized into the intestinal tract, is almost impossible to distinguish from a flare of inflammatory bowel disease. Optimal management of this condition begins with using the right diagnostic test and definitions. Viral load quantification on biological samples (blood or tissue) by real time-polymerase chain reaction not only shows the best diagnostic accuracy but also makes it possible to distinguish between viral reactivation, infection, and disease, the clinical approach to which differs substantially. A crucial role is also played by the host virus-specific T-cell immunity, monitoring of which may improve patient management. In this regard, the advent of new therapeutic and vaccination tools, as in the transplantation field, is expected to improve patients' outcome.