Chicago (CNN) -- The JW Marriott Chicago hotel said Friday it has removed its lobby fountain and closed parts of its luxury spa after health authorities determined them to be the likely source of a Legionnaires' disease outbreak that has now killed three people.
Health authorities said Friday there is no longer a health risk at the landmark hotel, but they urge people to seek medical attention if they stayed at the hotel during the affected dates of July 16 to August 15 and are now experiencing flu-like symptoms.
"We are secure in the testing results reported by (the Illinois Department of Public Health) that have informed this investigation and are encouraged by the hotels' cooperation and remediation plan," said Dr. Kathy Ritger of the Chicago Department of Public Health. "We believe there is no ongoing public health risk at the hotel at this time."
Health officials have confirmed 10 cases of Legionnaires' disease, including the three deaths. All of the victims visited or stayed at the hotel during the monthlong affected period.
The disease is a severe form of pneumonia and is contracted by breathing in small water droplets, whether from mist or vapor, contaminated with the Legionella bacteria. It is not transmitted from person to person.
Samples taken from the hotel's fountain as well as the women's locker room, men's locker room, swimming pool, and whirlpool located in the hotel's spa all tested positive for the same species of Legionella as were found in the ill patients, the Chicago Department of Public Health said.
Shower heads in guest rooms tested negative for the bacteria, the health department said.
Legionella are present at low levels in most water systems, the health department said, but they can flourish and pose a significant health risk when proper water quality is not maintained, even for a short period of time.
The health department said the hotel is following recommendations to remediate the "possible exposure settings" in its environment, and Marriott said it is now working with a water safety consulting company to install new clean water systems.
The disease usually develops two to 14 days after exposure to the bacteria and often begins with a headache, high fever, and chills, the health department says. By the second to third day, a person may develop symptoms of pneumonia like cough, chest pain, and shortness of breath.
Most victims recover, but between 5% and 30% of people who get the disease die, according to the U.S. Centers for Disease Control.
An outbreak of the disease in Philadelphia in 1976, largely among people attending a convention of the American Legion, led to its name.
An average of 30 cases of Legionnaires' disease is reported each year in Chicago, the city's health department said. There were 44 cases, including 1 death, in 2011.