The U.S. has entered emergency response mode as a cruise ship hit by a deadly hantavirus outbreak sails toward Tenerife, one of Spain’s Canary Islands, where it will evacuate nearly 150 passengers on board, including at least 17 Americans. State and local health officials in the U.S. are monitoring at least eight passengers who disembarked on April 24 and returned home. For the time being, those individuals are not being told to isolate, since they have not developed symptoms. As early as