Legionnaires’ disease is a serious type of pneumonia caused by Legionella bacteria. While it’s known for outbreaks in hospitals, hotels, and large buildings, one of the most common questions people ask is: “Is Legionnaires’ disease contagious?”
The short answer is no, but there’s a lot more you should know. We are here to address everything you need to understand about the transmission, risks, and prevention of Legionnaires’ disease.
What Does “Contagious” Mean in This Context?
A disease is considered contagious if it can be spread directly from person to person, such as through coughing, sneezing, or close contact. Common contagious illnesses include the flu, COVID-19, and the common cold.
Legionnaires’ disease is not contagious. You cannot catch it by being near someone who’s infected, nor by sharing drinks, touching surfaces, or breathing the same air.
How Do People Get Legionnaires’ Disease?
People get Legionnaires’ disease by inhaling mist or vapor that contains Legionella bacteria. This usually comes from contaminated water sources, such as:
- Hot tubs and spas
- Showerheads and faucets
- Decorative fountains
- Cooling towers (used in air conditioning and industrial cooling systems)
- Large plumbing systems
- Humidifiers
- Windshield wiper fluid without proper cleaning agent
Less commonly, people can become ill by aspirating drinking water, meaning the water “goes down the wrong pipe” and enters the lungs instead of the stomach.
Can Legionnaires’ Disease Spread From Person to Person?
No. The CDC, OSHA, and health departments agree: Legionnaires’ disease is not spread from person to person. It is caused by environmental exposure, not by human-to-human transmission.
This is true even during outbreaks. Each case stems from exposure to a common environmental source, not from contact with other people.
Has There Ever Been a Case of Human-to-Human Transmission?
There has been only one suspected case of human-to-human transmission ever reported (in Portugal, 2014), and it remains extremely rare and unconfirmed. For all practical purposes, the disease is considered non-contagious by public health agencies worldwide.
Is Pontiac Fever Contagious?
Pontiac fever is a mild, flu-like illness also caused by Legionella bacteria. Like Legionnaires’ disease, Pontiac fever is not contagious and doesn’t involve pneumonia. It typically resolves on its own without antibiotics.
What Are the Symptoms of Legionnaires’ Disease?
Symptoms generally begin 2 to 14 days after exposure and may include:
- High fever (often above 104°F)
- Dry or productive cough
- Shortness of breath
- Muscle aches
- Headaches
- Nausea, vomiting, or diarrhea
- Confusion or mental changes
These symptoms overlap with other illnesses like pneumonia and flu, so diagnostic testing (such as urine antigen or sputum tests) is essential for confirmation.
Who Is at the Greatest Risk?
While most healthy people exposed to Legionella do not get sick, the disease tends to affect those with:
- Age 50+
- Current or former smoking habits
- Chronic lung diseases (like COPD or emphysema)
- Weakened immune systems (from illness or medications)
- Recent surgery or hospitalization
- Conditions like diabetes, cancer, kidney, or liver failure
How Is Legionnaires’ Disease Treated?
Legionnaires’ disease is treated with antibiotics, such as:
- Levofloxacin
- Azithromycin
- Doxycycline
- Rifampin
Most patients require hospitalization, and severe cases may involve oxygen therapy or mechanical ventilation.
The disease is fatal in 5–10% of treated cases — and up to 80% if left untreated, which is why early diagnosis and treatment are critical.
How Can I Protect Myself if Someone Near Me Has Legionnaires’ Disease?
Since the disease is not contagious, you do not need to isolate from an infected person or take special precautions. Focus instead on environmental prevention, such as:
- Ensuring building water systems are properly maintained
- Regularly disinfecting hot tubs, humidifiers, and fountains
- Avoiding stagnant or warm water systems
- Using genuine windshield washer fluid in vehicles
What Should I Do if There’s an Outbreak in My Building or Community?
If a public health department reports a cluster or outbreak, such as the recent one in Central Harlem, you should:
- Monitor yourself for symptoms
- Seek prompt medical attention if symptoms appear
- Inform your healthcare provider about the outbreak and your possible exposure
You do not need to avoid drinking water or using air conditioning, unless specifically instructed otherwise. Most outbreaks are tied to aerosolized mist, not drinking water or HVAC systems without water.
Legal Options and Next Steps After a Legionnaires’ Disease Diagnosis
No, Legionnaires’ disease is not contagious. It does not spread from person to person. Instead, the disease is caused by inhaling contaminated water vapor or aspirating tainted water from environmental sources like hot tubs or cooling towers.
If you or a loved one has been diagnosed with Legionnaires’ disease, especially as part of an outbreak linked to a building or facility, you may want to consult with a Legionnaires’ disease attorney. These legal professionals can help determine whether your illness may be the result of negligence in water system maintenance—and if so, whether you’re entitled to compensation.
sc name=”cta-break”][/sc]
