What is legionnaires’ disease?
Legionnaires’ disease is a severe form of pneumonia — lung inflammation usually caused by infection. Legionnaires’ disease is caused by a bacterium known as legionella.
You can’t catch legionnaires’ disease from person-to-person contact. Instead, most people get legionnaires’ disease from inhaling the bacteria. Older adults, smokers and people with weakened immune systems are particularly susceptible to legionnaires’ disease.
The legionella bacterium also causes Pontiac fever, a milder illness resembling the flu. Separately or together, the two illnesses are sometimes called legionellosis. Pontiac fever usually clears on its own, but untreated legionnaires’ disease can be fatal. Although prompt treatment with antibiotics usually cures legionnaires’ disease, some people continue to experience problems after treatment.
How common is legionnaires’ disease?
Legionnaires’ is not rare. It is perceived as rare only because most cases are never detected, and not all detected cases are reported to public health authorities. Because under-diagnosis and under-reporting make incidence of the disease difficult to estimate, figures have varied widely. Please discuss with your doctor for further information.
What are the symptoms of legionnaires’ disease?
Legionnaires’ disease usually develops two to 10 days after exposure to legionella bacteria. It frequently begins with the following signs and symptoms:
- Muscle pain
- Fever that may be 104 F (40 C) or higher
By the second or third day, you’ll develop other signs and symptoms that may include:
- Cough, which may bring up mucus and sometimes blood
- Shortness of breath
- Chest pain
- Gastrointestinal symptoms, such as nausea, vomiting and diarrhea
- Confusion or other mental changes
Although legionnaires’ disease primarily affects the lungs, it occasionally can cause infections in wounds and in other parts of the body, including the heart.
A mild form of legionnaires’ disease — known as Pontiac fever — may produce signs and symptoms including a fever, chills, headache and muscle aches. Pontiac fever doesn’t infect your lungs, and symptoms usually clear within two to five days.
There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.
When should I see my doctor?
See your doctor if you think you’ve been exposed to legionella bacteria. Diagnosing and treating legionnaires’ disease as soon as possible can help shorten the recovery period and prevent serious complications. For people at high risk, prompt treatment is critical.
What causes legionnaires’ disease?
The bacterium Legionella pneumophila is responsible for most cases of legionnaires’ disease. Outdoors, legionella bacteria survive in soil and water, but rarely cause infections. Indoors, though, legionella bacteria can multiply in all kinds of water systems — hot tubs, air conditioners and mist sprayers in grocery store produce departments.
Although it’s possible to contract legionnaires’ disease from home plumbing systems, most outbreaks have occurred in large buildings, perhaps because complex systems allow the bacteria to grow and spread more easily.
What increases my risk for legionnaires’ disease?
There are many risk factors for legionnaires’ disease, such as:
- Smoking damages the lungs, making you more susceptible to all types of lung infections.
- Have a weakened immune system as a result of HIV/AIDS or certain medications, especially corticosteroids and drugs taken to prevent organ rejection after a transplant.
- Have a chronic lung disease such as emphysema or another serious condition such as diabetes, kidney disease or cancer.
- Are 50 years of age or older.
Legionnaires’ disease is a sporadic and local problem in hospitals and nursing homes, where germs may spread easily and people are vulnerable to infection.
Diagnosis & treatment
The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.
How is legionnaires’ disease diagnosed?
Legionnaires’ disease is similar to other types of pneumonia. To help identify the presence of legionella bacteria quickly, your doctor may use a test that checks your urine for legionella antigens — foreign substances that trigger an immune system response. You may also have one or more of the following:
- Blood tests
- Chest X-ray, which doesn’t confirm legionnaires’ disease but can show the extent of infection in your lungs
- Tests on a sample of your sputum or lung tissue
- A CT scan of your brain or a spinal tap (lumbar puncture) if you have neurological symptoms such as confusion or trouble concentrating
How is legionnaires’ disease treated?
Legionnaires’ disease is treated with antibiotics. The sooner therapy is started, the less likely the chance of serious complications or death. In many cases, treatment requires hospitalization. Pontiac fever goes away on its own without treatment and causes no lingering problems.
Lifestyle changes & home remedies
What are some lifestyle changes or home remedies that can help me manage legionnaires’ disease?
The following lifestyles and home remedies might help you cope with legionnaires’ disease:
- Outbreaks of legionnaires’ disease are preventable, but prevention requires meticulous cleaning and disinfection of water systems, pools and spas.
- Avoiding smoking is the single most important thing you can do to lower your risk of infection. Smoking increases the chances that you’ll develop legionnaires’ disease if you’re exposed to legionella bacteria.
If you have any questions, please consult with your doctor to better understand the best solution for you.
Hello Health Group does not provide medical advice, diagnosis or treatment.
Review Date: July 20, 2017 | Last Modified: July 20, 2017
Legionnaires' disease. http://www.mayoclinic.org/diseases-conditions/legionnaires-disease/home/ovc-20242041. Accessed July 19, 2017.
How common is Legionnaires disease? http://hcinfo.com/about/legionnaires-disease/how-common-is-legionnaires-disease/. Accessed July 19, 2017.