What Causes Legionnaires' Disease?
You can get Legionnaires' disease (LD) by breathing in tiny water droplets (aerosolization) containing Legionella bacteria. These droplets can come from sources like:
- Showers
- Hot tubs
- Decorative fountains
You can get sick from Legionella bacteria if:
- You breathe in the water as a mist
- The water goes up your nose
- The water gets into an open cut or would (less common)
Cases are more common in the summer and early fall when temperatures are warmer, but LD can occur any time of year.
Important to know:
- Most people exposed to Legionella don't get sick.
- You can't catch LD from another person.
How Soon Do Symptoms Appear?
Symptoms usually appear 2 to 14 days after you breathe in the bacteria. For Pontiac fever (a milder illness caused by Legionella), symptoms appear sooner, usually within a few hours to 3 days.
Symptoms of Legionnaires' Disease
Early symptoms of both LD and Pontiac fever are similar and can include:
- Loss of appetite
- Tiredness
- Headache
- High fever with chills (often reaching 102-105°F)
Other common symptoms, especially with LD, can include:
- Stomach pain
- Cough (often without mucus)
- Diarrhea
Seriousness of LD
Legionnaires' disease can be very serious. Up to one-third of people hospitalized with LD may die. Pontiac fever, on the other hand, is much milder and goes away on its own in a few days.
How is Legionnaires' Disease Diagnosed?
Doctors diagnose LD by testing urine, blood, or samples from your lungs to find the Legionella bacteria.
What is the treatment for Legionnaires’ disease?
LD is treated with antibiotics. Pontiac Fever resolves without
treatment.
How Common is Legionnaires' Disease?
In the United States, an estimated 8,000 to 18,000 people get LD each year. Many more people may be infected with the Legionella bacterium but have only mild symptoms or no illness at all.
Outbreaks of LD often receive media attention, but this disease usually occurs as a single, isolated case not associated with any recognized outbreak. This is because the infection is not transmitted from person to person. When outbreaks do occur, they are usually recognized in the summer and early fall, but cases may occur year-round.
Who is at Risk for Legionnaires' Disease?
People of any age may get LD, but the illness most often affects middle-aged and older persons, particularly those who smoke cigarettes or have chronic lung disease.
Other groups at increased risk include:
- People whose immune system is suppressed by chronic medical conditions such as cancer, kidney failure requiring dialysis, diabetes, or AIDS.
- People who take drugs that suppress the immune system.
Pontiac fever, a milder form of illness caused by Legionella, most commonly occurs in people who are otherwise healthy.
Where are Legionella Bacteria Found?
Legionella bacteria live in the environment, especially in water. However, the bacteria reproduce to high numbers in warm, stagnant water (90-100°F), such as that found in:
- Certain plumbing systems and hot water tanks
- Cooling towers and evaporative condensers of large air-conditioning systems
- Whirlpool spas
Cases of LD have been identified throughout the US and in several foreign countries. It is believed to occur worldwide.
How Can Legionnaires' Disease be Prevented?
Improved design and maintenance of cooling towers and plumbing systems to limit the growth and spread of Legionella organisms are the foundations of LD prevention. Public health officials seek the sources of the disease and recommend appropriate prevention and control measures, such as decontamination of the water source.
Take steps at home
to avoid getting sick from germs that grow in pipe slime and devices that use water.
- Flush faucets and showerheads that have not been used in a while (for example, a week or more) before using them again.
- Clean and mantain devices that use water (for example, humidifiers and neti pots).
Where can I get more information about Legionella?
From the Centers for Disease Control and Prevention (CDC)
