A substantial proportion (at least 15 per cent) of the global cancer burden is attributable to known infectious agents such as HPV, HBV and Helicobacter pylori. It is possible that infectious agents may have a still greater role in cancer etiology, but traditional methods for finding them have limited sensitivity. The Holt Lab finds pathogens by their sequence signatures in human tissues using genomic methods. Application of these methods to colorectal carcinoma identified a strong link to the emerging pathogen Fusobacterium nucleatum. Cancer associated infectious agents are of potential utility as targets for vaccination, treatment and prevention.