There were echoes of the 2014 Ebola scare in Denver Sunday after a man who'd been working with virus victims in the Congo suddenly became extremely ill. The man, who returned to the US a few days ago, was hospitalized and placed in isolation, as were three members of the ambulance crew that picked him up. "We felt that, if he had Ebola, then he could be very communicable ... We had no wiggle room to be wrong," Denver Health Chief Medical Officer Connie Price tells the Denver Post. Officials said Sunday night that initial tests for Ebola had come back negative, CBS Denver reports. Price says Ebola symptoms can resemble those of other illnesses, including flu and appendicitis. (More Ebola stories.)