An outbreak of Legionnaires’ disease cases linked to a Florida gym has brought cases to a 10-year high in the state.
The Orange County “gym exposure” outbreak includes 14 cases of the disease, the Florida Department of Health said.
Legionnaires’ disease is a serious type of pneumonia caused by Legionella bacteria, according to the health department. Lung infection can be mild for healthy people but serious and sometimes fatal for certain groups at risk.
“The most common way for someone to get sick is by breathing in a mist that is in it Legionella,” according to the US Centers for Disease Control and Prevention.
The gym outbreak brings the total number of cases in Orange County in 2025 to 82, the highest in the state. Florida reported a total of 72 confirmed cases of legionellosis in November. Florida saw 665 cases in 2025.
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Case reports of legionella also include Pontiac fever, which is a mild infection caused by the same type of Legionella bacteria that causes Legionella disease.
Florida’s increase in Legionnaires’ cases reflects a national trend, according to the US Centers for Disease Control and Prevention. Here’s what you need to know about the disease:
What is Legionnaires’ disease? What are the symptoms?
Most healthy people exposed to Legionella do not get sick or show mild Pontiac fever. Older adults and people who smoke have a higher risk of getting the more serious cases of Legionnaires’ disease and should seek immediate treatment.
The first signs of Legionnaires’ disease tend to mimic the flu. People often develop a high fever, headache and muscle aches between two and 10 days after contact with Legionella bacteria, according to the Mayo Clinic.
A day or two later, people who have contracted Legionnaires’ disease often report coughing up mucus and sometimes blood, shortness of breath, chest pain, nausea, vomiting, diarrhea, confusion or other mental changes.
How does Legionnaires’ disease spread?
The Legionella bacterium thrives in warm, aquatic environments and is generally spread through aerosolized water that is then inhaled, such as showers and spas. Cooling towers, water systems located on buildings that control the temperature of cooling systems such as air conditioning, can also be a source of spillage.
It is not transmitted from person to person, according to the Florida Department of Health. Rather, Legionnaires’ disease is usually contracted when someone inhales water droplets that are contaminated with Legionella bacteria.
The CDC estimates that about nine out of 10 outbreaks are caused by problems that could have been prevented with effective water management, including for hot tubs, plumbing systems and cooling towers.
Is Legionnaires’ disease fatal? Who is most at risk?
About one in 10 people who get Legionnaires’ disease die from complications related to the disease, according to the CDC.
“For those who get Legionnaires’ disease during a visit to a health care facility, about 1 in 4 will die,” the CDC website says.
Current or former smokers, people aged 50 and over and people with certain health issues or conditions are at greater risk of getting sick. Those conditions include:
CDC data also show that some groups of people and factors have higher incidence rates:
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Northeast and Midwest regions
US cases of Legionnaires’ disease are on the rise
Since 2000, the United States has seen legionellosis rates increase ninefold. Reports peaked in 2018 and fell to a five-year low during the 2020 COVID-19 pandemic. The reported cases returned in 2021 and are increasing again.
Between 8,000 and 18,000 people are hospitalized with Legionnaires’ disease each year in the United States, the Florida health department said.
The CDC is investigating a 2025 Legionnaires’ group in New York City that has been blamed for at least seven deaths, 90 hospitalizations and 114 cases over the summer. The outbreak is suspected to be caused by cooling towers harboring the bacteria in downtown Harlem.
The Harlem cases arose in late July and led officials to work to remedy the issues with a dozen cooling towers across five zip codes. Officials declared the cluster on August 29.
Climate change has been pointed out as a contributing factor to the increase in Legionnaires’ cases; warmer and more humid conditions mean more places are adding cooling infrastructure that can breed bacteria.
Contribution: Eduardo Cuevas, USA TOD
This article originally appeared on the Pensacola News Journal: Florida Legionnaires’ outbreak blamed on ‘gym exposure’