Porcine Deltacoronavirus - Koch's Postulates FulfilledKoch’s Postulates Fulfilled Dr. Dick Hesse, Kansas State University, shares the background of the discovery of the deltacoronavirus. While not a prominent as PEDv, deltacoronavirus is a pathogen and is out there, having been reported in at least 22 US states with continued reports being filled. Dr. Hesse says there still are many gaps in the understanding of deltacoronavirus, including biological and physical transmission.