What is Legionnaires’ Disease?

Symptoms and Exposure

What are the symptoms of Legionnaires’ disease?

Symptoms initially resemble the flu, progressing to severe pneumonia. Early signs include slight fever, headache, muscle aches, low energy, and loss of appetite. More severe symptoms develop later, such as:

• • • High fever (102° to 105°F, or 39° to 41°C)
    • Cough, initially dry but later producing phlegm
    • Shortness of breath (dyspnea)
    • Chills
    • Chest pains
    • Gastrointestinal issues like diarrhea and nausea

How common is Legionnaires’ disease?

Approximately 6,000 cases are reported annually in the United States.

What causes Legionnaires’ disease?

Legionnaires’ disease is caused by Legionella bacteria, specifically Legionella pneumophila, which is the most common species responsible for human infections.

How is Legionnaires’ disease contracted?

The disease is contracted by inhaling or ingesting water contaminated with Legionella bacteria. Sources include cooling towers, humidifiers, showers, and sinks.

How soon after exposure do symptoms appear?

Symptoms typically manifest within 2-10 days after exposure.

Does everyone exposed to Legionella bacteria develop Legionnaires’ disease?

No, fewer than 5% of people exposed to contaminated water will develop the disease, as most individuals have natural resistance.

Who is at higher risk for Legionnaires’ disease?

Higher risk groups include:

• • • • Older adults
      • Heavy smokers
      • Individuals with weakened immune systems (e.g., cancer patients, HIV-infected individuals)
      • Those with chronic diseases (e.g., diabetes, respiratory disease)
      • Organ transplant recipients
      • People on certain medications (e.g., corticosteroids)
      • Heavy alcohol consumers

Is Legionnaires’ disease contagious?

No, it is not transmitted from person to person.

Monitoring and Testing

How is Legionella bacteria monitored or tested?

The U.S. Water lab technicians test water samples from suspected sources. Air testing is generally not recommended due to the high likelihood of false negatives. Water samples are analyzed by certified microbiological laboratories experienced in Legionella detection. It’s crucial to follow proper collection, storage, and transportation procedures for accurate results.

What should I do if I suspect Legionella contamination in my building’s water system?

Contact U.S. Water’s Elite Laboratory to test and evaluate the water system. Follow recommended cleaning and disinfection procedures if Legionella is detected.

Exposure Sources

How did Legionnaires’ disease get its name?

The name comes from the first recognized outbreak in 1976, during an American Legion convention in Philadelphia, where over 200 attendees developed pneumonia caused by the newly identified Legionella pneumophila.

Are Legionella bacteria widespread?

Yes, Legionella bacteria are found in natural water sources like rivers, lakes, and ponds, as well as man-made water systems.

Can you get Legionnaires’ disease from natural water sources?

It is unlikely, as natural water sources typically contain low levels of Legionella.

Can Legionnaires’ disease be contracted from air conditioning systems?

Yes, but primarily from cooling towers associated with air conditioning systems, not from home or car air conditioning units.

Are there guidelines for preventing Legionella in public water systems?

Yes, public health agencies provide guidelines for maintaining water systems, including routine testing, cleaning, and using biocides to control Legionella growth.

What man-made water sources pose the greatest risk?

High-risk sources include cooling towers, evaporative condensers, humidifiers, misters, showers, faucets, and whirlpool baths. Inhalation or ingestion of contaminated water mist from these sources can lead to the disease.

What water conditions promote Legionella growth?

Warm, stagnant water is ideal for Legionella growth. The bacteria thrive between 68° and 122°F (20° – 50°C), with optimal growth between 95° and 115°F (35° – 46°C). Rust, scale, and other microorganisms also support Legionella proliferation.

How can Legionnaires’ disease be prevented?

Preventive measures include:

• • • Regular maintenance and cleaning of cooling towers and evaporative condensers
    • Maintaining water heaters at 140°F (60°C) and water temperature at 122°F (50°C) or higher at the faucet
    • Avoiding water stagnation by frequently flushing unused water lines
    • Protecting large water storage tanks from sunlight to prevent warming

Can contaminated water systems be cleaned?

Yes, special cleaning procedures, such as using chlorine-producing chemicals or high water temperatures, can eliminate Legionella. Professional assistance is recommended.

Pontiac Fever

Can Legionella bacteria cause other diseases?

Yes, Legionella bacteria can also cause Pontiac fever, a milder, flu-like illness.

How does Pontiac fever differ from Legionnaires’ disease?

Pontiac fever causes flu-like symptoms, including fever, headache, fatigue, muscle and joint pain, chills, nausea, and a dry cough. Unlike Legionnaires’ disease, Pontiac fever does not lead to pneumonia and resolves without antibiotics in 2-5 days.

Are there other differences between Legionnaires’ disease and Pontiac fever?

Yes, Pontiac fever has a higher infection rate (up to 90%) among exposed individuals and a shorter incubation period of 1-2 days compared to Legionnaires’ disease.

By understanding and addressing these key aspects, you can significantly reduce the risk of Legionnaires’ disease and ensure a safer environment for yourself and others