Legionnaire Disease: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Legionnaire Disease?
A pulmonologist (a lung doctor) or an infectious disease doctor treats Legionnaire disease with antibiotics, and you will likely need care in a hospital. Most people recover, especially if they were healthy when they got sick. Getting treatment early can increase the chances of getting better. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is Legionnaire disease?
Legionnaire disease is a serious type of pneumonia, a lung infection. It comes from Legionella bacteria. The disease got its name from a 1976 outbreak at an American Legion convention in Philadelphia. The germs grow in water systems built by people. You get sick when you breathe in tiny water droplets that hold the bacteria. Legionella can also cause Pontiac fever, a milder flu-like illness that does not infect the lungs.
Symptoms
Symptoms usually start 2 to 14 days after you breathe in the bacteria. They feel a lot like other types of pneumonia. Signs include:
- Cough.
- High fever and chills.
- Headache.
- Chest pain.
- Shortness of breath.
- Muscle aches and tiredness.
Some people also have stomach problems. These include nausea, vomiting, diarrhea, and belly pain. Confusion or other mental changes can also happen. Legionnaire disease can cause serious problems. These include respiratory failure, when the lungs cannot take in enough oxygen. It can also cause kidney failure and sepsis, a dangerous infection that spreads through the body. About 1 out of every 10 people who get sick die from it.
Causes and who gets it
Legionella bacteria live naturally in fresh water, such as lakes and rivers, and in soil. People usually get sick when the bacteria grow in man-made water systems. These include hot tubs, fountains, and the plumbing of large buildings like hotels or nursing homes. You get sick by breathing in mist or droplets from these systems. Drinking the water rarely causes illness unless it slips into your lungs. In general, the disease does not spread from person to person. Outbreaks happen when many people share the same water source.
Most healthy people who meet the bacteria do not get sick. Your risk is higher if you:
- Are over age 50.
- Smoke or used to smoke.
- Have a long-lasting disease such as diabetes or kidney failure.
- Have a long-lasting lung disease such as COPD, a disease that makes breathing hard.
- Have a weakened immune system from HIV, cancer, or medicines.
- Live in a long-term care facility or recently stayed in a hospital.
How doctors diagnose it
The symptoms look like other kinds of pneumonia, so tests are needed. Your doctor will order a chest x-ray to check for pneumonia. If it is there, lab tests look for Legionella. A urine test or a sputum test, which checks phlegm from the lungs, can find the bacteria. A blood test can show if your body has been exposed to them.
Treatment
Legionnaire disease is treated with antibiotics, medicines that kill bacteria. Most people need care in a hospital. Getting treatment early raises your chance of a full recovery. Most people recover, especially if they were healthy before they got sick.
When to see a doctor
Call 911 if you have chest pain, shortness of breath, or confusion. See a doctor soon if you have a cough with a fever, especially if you are in a higher-risk group, because treating early helps. Legionnaires' disease can cause life-threatening complications such as respiratory failure, kidney failure, and sepsis.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. This kind of doctor can order a chest x-ray and lab tests that check for the bacteria.
Common questions
Is Legionnaire disease contagious?
In general, no. It is not spread from person to person. You get it by breathing in water droplets that hold the bacteria. Outbreaks happen when many people share the same water source.
How serious is Legionnaire disease?
It is a serious type of pneumonia and can be life-threatening. About 1 out of every 10 people who get sick die from complications. Most people recover with antibiotic treatment, especially when care starts early.
Can you get it from drinking water?
Drinking water with the bacteria rarely makes you sick. The danger comes from breathing in mist or droplets. It can make you sick if contaminated water slips into your lungs.
Who is most at risk?
People over age 50, smokers, and people with long-lasting lung disease face higher risk. So do people with a weakened immune system. Healthy people who meet the bacteria usually do not get sick.
Can it be prevented?
You can lower your risk by caring for water systems. Clean humidifiers and other water devices often. If a faucet or showerhead has not been used for a week, run hot and cold water for at least two minutes first. Avoid hot tubs or fountains that may be poorly kept.
Sources
- MedlinePlus - Legionnaires' Disease
- Centers for Disease Control and Prevention - About Legionnaires' Disease
- Centers for Disease Control and Prevention - Clinical Features of Legionnaires' Disease and Pontiac Fever
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
