Orange County health officials say they have been notified of eight cases of the disease in the month of September.
The infection is treatable, though about one in 10 people who contract Legionnaires' - usually those over 50 with weakened immune systems or chronic lung disease - die from it.
The remaining three were Orange County residents who did not visit the park but lived or traveled in Anaheim.
After the Orange County Health Care Agency reported an increase of Legionnaires' cases in Anaheim, the park investigated and found two towers had "had elevated levels of Legionella bacteria". One patient, who hadn't visited the park, has died. That person had not visited Disneyland.
According to Legionella.org, "Legionnaires' disease is a severe, often lethal, form of pneumonia".
Disneyland voluntarily shut down two water cooling towers in one of its backstage areas after discovering they contained high levels of the bacteria that causes Legionnaire's, according to the Orange County Register. Good's email statement didn't indicate if any of those who contracted the disease were related to each other.
In a statement, Dr. Pamela Hymel, chief medical officer for Walt Disney Parks and Resorts, said Disneyland learned about the Legionnaires' cases on October 27.
According to the OCHCA, the Legionnaire's disease exposure period ranged from September 12 to September 27, Hymel said, adding that Disney thoroughly reviewed all regular water testing for the resort, "including work performed by contracted third-party experts", and "implemented additional redundant testing of other cooling towers on our property".
"These towers were treated with chemicals that destroy the bacteria and are now shut down", said Hymel. The county contacted Disney after it discovered several had gone to the park.
The county agency issued an order November 8 requiring Disney to take the towers out of service until they are shown to be free from contamination. The incubation period is two to 10 days before symptoms appear, after exposure to the bacteria. That outbreak, which sickened 182 and resulted in 29 deaths, was traced to the convention hotel's air conditioning system. It is not contagious from person to person. A similar upward trend has been seen nationally and elsewhere in Southern California, according to the health care agency, though what's causing that is unclear.