Officials with the U.S. Centers for Disease Control and Prevention confirmed the nation’s first coronavirus case of unknown origin Wednesday in Northern California in the latest sign of the virus’ rapid spread. “It is a confirmed case. There is one in Northern California,” CDC spokesman Scott Pauley told The Sacramento Bee just before 4 p.m. Wednesday. Pauley declined to elaborate. It was immediately unknown where in Northern California the case was discovered, but officials have begun to trace the person’s contacts as they sleuth out where and how the person may have become infected and whether others have been exposed,