The threat forced officials to quarantine the driver as a precaution and to take the bus out of service while it undergoes a thorough scrub down, likely costing taxpayers thousands of dollars, said Metro spokesman Marc Littman.
While the Los Angeles County Department of Public Health believes the threat was a hoax, the multi-agency response was broadcast on television amid a backdrop of unending cable news headlines on the worst Ebola outbreak in history.
Metro already has protocols in place to deal with public health scares, but the agency is seeking advice from county public health officials, as well as the Centers for Disease Control and Prevention, on how they should handle Ebola threats in the future.
Littman recalled the drain on resources during the anthrax scare of 2001. At the time, authorities responded to numerous threats that turned out to be hoaxes, but each time, they were treated seriously, as was Monday's case.
"We are taking it very serious," he said. "We want to send a strong message to the public: If you are going to pull a stunt, we are going to go after you."
The incident is being investigated as a possible terrorist threat because of the fear it incited, Littman said. The FBI is also now involved in the investigation as authorities review surveillance footage taken from seven cameras on the bus.
"You can't create public hysteria and you can't disrupt service," he said.
Officials are still trying to determine the identity of the man who was donning a surgical mask before shouting the threat and bolting off the Line 33 bus with a female companion. But the incident has raised concerns about copycats and how Metro should respond in the future.
The bus driver, meanwhile, has been released from the hospital in "good condition," but will not be returning to work for at least three weeks as doctors continue to monitor his health -- all the while remaining on Metro's payroll, Littman said.
"There are people out there that think it's funny, but it's not," he added. "We are not going to put up with it."