Officials are preparing to test dogs, cats and even rats to determine whether they are carriers of the dangerous Middle Eastern Respiratory Syndrome. Scientists suspect the deadly illness — characterized by fever, cough and breathing difficulties — crossed over from animals to humans, and it’s already been traced to camels. But the way the disease is spreading indicates that other animals may be carriers. Scientists fear the disease could spread quickly if it’s not brought under control. Thirty percent of people who get Mers die, and 200 people have succumbed to it since 2012.