Ten of the victims died, the Orlando Sentinel reports.

Legionnaires' disease, a severe respiratory infection, was first identified after an outbreak at an American Legion convention at a Philadelphia hotel in 1976 that killed 29 people. The bacterium grows in water and is sometimes found in swimming pools, hot tubs and air conditioning systems.

Orange County health officials announced last week that two tourists who stayed at a hotel near Universal Studios had been diagnosed with the disease.

Health officials say Legionnaires' remains a minor risk in Florida, given the millions of tourists who visit the state each year. Dain Weister of the Orange County Health Department said there were 13 cases in a county with a population of 1 million -- plus the tourists who come to Disney World and other resorts.

"It's not an astronomical number," Weister said. "It's not a sign we've got a major problem."