Is a gun like a virus, a car, tobacco or alcohol? Yes, say public health experts, who in the wake of recent mass shootings are calling for a fresh look at gun violence as a social disease."What I'm struggling with is, is this the new social norm? This is what we're going to have to live with if we have more personal access to firearms," said Dr. Stephen Hargarten, emergency medicine chief at Froedtert Hospital and director of the Injury Research Center at the Medical College of Wisconsin. "We have a public health issue to discuss. Do we wait for the next outbreak or is there something we can do to prevent it?"