What Is Legionnaires’ Disease? What to Know About the Napa County Outbreak

One person has died and 11 others were hospitalized due to a Legionnaires’ disease outbreak in Napa County, California, according to a statement from the county released August 3. The 12 people—all Napa County residents—were diagnosed since July 11, and three are still hospitalized, the statement said.

Legionnaires’ disease is a type of pneumonia (lung infection) caused by bacteria called Legionella that grow in warm water, the statement said. People can get sick after breathing in droplets or swallowing water contaminated with Legionella, per the Centers for Disease and Prevention (CDC). Legionella can grow and spread in man-made water systems such as sink faucets, showerheads, decorative water fountains, hot tubs, hot water tanks or heaters, plumbing systems, and cooling towers, which are structures that are part of a building’s cooling system that contain water and a fan, per the CDC.

Napa County officials tested man-made water sources and found “high levels of Legionella bacteria” in a sample from the cooling tower at Embassy Suites Napa Valley, the statement said. None of the 12 residents diagnosed with Legionnaires’ had stayed in or visited the hotel. A Napa County health official said in the statement that during a Legionnaires’ outbreak it’s common to find more than one sore of Legionella; therefore, officials are still searching for other contaminated water sources.

The CDC says that Legionnaires’ is not generally spread person-to-person—meaning you’d most likely have to ingest or swallow droplets of the contaminated water to get sick—but acknowledges that this may be possible. The person who died from the current outbreak in Napa County was over 50 years old and had “high risk factors for severe disease,” per the statement. People at increased risk include former or current smokers, people with chronic lung disease, people with weak immune systems, people with cancer, people with underlying illnesses (such as kidney failure, liver failure, or diabetes), and people over 50, per the CDC.

The U.S. sees an estimated 25,000 Legionnaires’ cases each year, per the New York State Department of Health (NYSDOH); the disease can occur sporadically or in outbreaks. Symptoms of Legionnaires’ include shortness of breath, cough, fever, headaches, and muscle aches; it has also been associated with nausea, diarrhea, and confusion, per the CDC, which notes that Legionnaires’ symptoms usually occur within two to 14 days of exposure to Legionella. However, it can take longer for these signs to show up.

If you develop the symptoms associated with Legionnaires’, you should see a doctor immediately, per the CDC. Multiple tests can be done to provide an accurate diagnosis. A chest X-ray can confirm that a person has pneumonia; from there, doctors can take a urine test or a phlegm sample to determine whether the pneumonia was caused by Legionella bacteria. (Also worth noting: Legionella bacteria can cause a milder illness called Pontiac fever, which can be diagnosed with similar tests.) The CDC says that if you seek medical treatment for Legionnaires’ symptoms, you should let your provider know if you believe you have been exposed to Legionella, spent nights away from home, used a hot tub, or stayed in a hospital during the last two weeks.

Legionnaires’ can be treated with antibiotics, but the recovery period can last for a few weeks following illness, per the National Health Service (NHS) of the U.K. Treatment is successful for most people with the condition—though hospitalization may be required in severe cases. 

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