Researchers from the University of Southern Denmark have identified a previously unknown virus living inside Bacteroides fragilis, a common gut bacterium. While this bacterium is found in most healthy people, the virus it carries appears far more frequently in patients who develop colorectal cancer. The discovery may explain why the same bacterium shows up in both healthy individuals and cancer patients — the difference could lie in whether the bacterium is carrying this specific virus. The findings, drawn from a large Danish population study of roughly two million people, suggest that the interaction between gut bacteria and the viruses they harbor may be a key driver of cancer risk. Researchers hope this could eventually lead to earlier screening tools.
