REEDVILLE, Va. (AP) — While friendly close contact is essential to dolphin social bonds, sharing space and air can also quickly spread disease. To track a virus outbreak among East Coast dolphins, scientists are tracing the social networks of these playful animals in the Potomac River and Chesapeake Bay. Scientists say a highly contagious and lethal virus called cetacean morbillivirus is one of the biggest threats to dolphins and whales worldwide. Human disruptions to marine habitats, including chemical and plastic pollution, boat noise and warming temperatures, weaken marine mammals’ immune systems, leaving them more vulnerable to disease.