An outbreak of Legionnaires’ disease cases linked to a Florida gym has pushed the state’s case count to a decade-high.
The Florida Department of Health said the “gym exposure” outbreak in Orange County includes 14 cases.
Legionnaires’ disease is a severe form of pneumonia caused by Legionella bacteria, according to the health department. In healthy people, lung infections may be mild, but in certain high-risk groups, they can be severe and sometimes fatal.
“The most common way people get sick is by inhaling Legionella”, according to the U.S. Centers for Disease Control and Prevention.
The gym outbreak brings Orange County’s total number of cases in 2025 to 82, the highest in the state. A total of 72 confirmed cases of Legionnaires’ disease were reported in Florida in November. There have been 665 cases in Florida in 2025.
Before: An obscure disease is spreading through air conditioners
Legionnaires’ disease case reports also include Pontiac fever, a milder infection caused by the same type of Legionella bacteria that causes Legionnaires’ disease.
The rise in cases among veterans in Florida mirrors national trends, according to the 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 develop the milder form of Pontiac fever. Older adults and smokers are at higher risk for more severe forms of Legionnaires’ disease and should seek treatment immediately.
The first symptoms of Legionnaires’ disease are often similar to those of the flu. According to the Mayo Clinic, people often develop high fever, headache, and muscle aches within 2 to 10 days after being exposed to Legionella.
After a day or two, people infected with Legionnaires’ disease often report a cough that may produce mucus and sometimes blood, shortness of breath, chest pain, nausea, vomiting, diarrhea, confusion, or other mental changes.
How is Legionnaires’ disease spread?
Legionella thrives in warm aquatic environments and is often spread through inhalation of aerosolized water, such as in showers and spas. Cooling towers are water systems located on top of buildings that control the temperature of cooling systems such as air conditioners and can also be sources of transmission.
It is not spread from person to person, according to the Florida Department of Health. Instead, Legionnaires’ disease is usually contracted when someone inhales water droplets contaminated with Legionella bacteria.
The CDC estimates that about nine out of 10 outbreaks are caused by problems with effective water management, including problems with hot tubs, plumbing systems and cooling towers.
Is Legionnaires’ disease fatal? Who is most at risk?
According to the Centers for Disease Control and Prevention, approximately 1 in 10 people with Legionnaires’ disease die from complications related to the disease.
“For those who contract Legionnaires’ disease while staying at a health care facility, about one in four will die,” the CDC website states.
Current or former smokers, people 50 years or older, and people with certain health problems or conditions are at higher risk. These conditions include:
CDC data also shows that certain groups and factors have higher rates:
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Northeast and Midwest regions
Legionnaires’ disease cases on the rise in US
Since 2000, the incidence of Legionnaires’ disease in the United States has increased ninefold. The number of reported cases peaked in 2018 and fell to a five-year low during the 2020 COVID-19 pandemic. The number of reported cases rebounded in 2021 and is rising again.
The Florida Department of Health says 8,000 to 18,000 people in the United States are hospitalized with Legionnaires’ disease each year.
The Centers for Disease Control and Prevention is investigating the 2025 veterans cluster in New York City that is believed to have caused at least seven deaths, 90 hospitalizations and 114 cases over the summer. The outbreak is suspected to have been caused by bacteria carried by a cooling tower in central Harlem.
The Harlem cases popped up in late July, prompting officials to work on fixing problems at more than a dozen cooling towers in five ZIP codes. Officials declared the cluster over on August 29.
Climate change is thought to be a factor in the increase in cases among veterans; hotter, more humid conditions mean more places are adding cooling infrastructure that can harbor bacteria.
Contributed by Eduardo Cuevas, USA Today
This article originally appeared in Pensacola News Journal: Florida Legion outbreak blamed on ‘gym exposure’