A dozen cases of the bacterial illness were discovered approximately three weeks ago, the Orange County Health Care Agency confirmed to The Associated Press.
Nine of the visitors had visited Disneyland Park in September before developing the illness, according to the paper, citing the Orange County Health Care Agency.
Legionnaire's Disease is a serious lung infection most often caused by inhaling microscopic water droplets tainted by the bacteria legionella. People who develop symptoms may experience fever, cough, chills, shortness of breath, headaches, muscle aches and diarrhea.
The other three cases were among residents of Anaheim, but they did not visit the park during the outbreak. Those towers were chemically treated and shut down to eliminate further infection.
'There is no known ongoing risk associated with this outbreak, ' the agency said. In this photo, English-Irish boy band The Wanted performs "Santa Claus is Coming To Town" while taping the Disney Parks Christmas Day Parade TV special at the Magic Kingdom park at Walt Disney World Resort in Lake Buena Vista, Florida, Dec. 6, 2013.
The towers are near the New Orleans Square Train Station, more than 100 feet away from parts of the theme park accessible to guests, a Disneyland Resort spokeswoman said Friday, the Los Angeles Times reported.
One individual, who did not visit the park, died from the disease although they were already suffering from other health issues. An employee working in the facility also got infected with the same disease.
Nine people have contracted Legionnaire's disease after visiting Disneyland in Anaheim, Calif.
Disney shut down the two water cooling towers after officials detected high levels of the bacteria from the virus, according to reports. Older people and those with health issues are particularly at risk.
The disease can be treated with antibiotics. Disney took the towers out of service on November 1, performed more testing and disinfection, and brought them back into service on November 5. The towers were taken out of service November 1, disinfected, went back in operation on November 5 but were shut down again Tuesday and will remain offline until tests confirm they are free from contamination, according to the park and the county health agency.