Legionnaires’ Disease Fact Sheet

Legionnaires’ disease is a severe form of pneumonia caused by the bacterium Legionella pneumophila. It spreads through inhaling contaminated water droplets from sources like cooling towers, air-conditioning systems, hot tubs, and plumbing systems. While not spread from person to person, outbreaks can occur in buildings with improperly maintained water systems. The disease primarily affects older adults, smokers, and those with weakened immune systems.

Causes and Transmission
  • Bacteria: Caused by Legionella pneumophila, which thrives in warm water environments.
  • Aerosolized Water Droplets: Infection occurs when people inhale tiny contaminated water droplets from mist or vapor.
  • Common Sources: Cooling towers, air conditioning units, hot tubs, humidifiers, fountains, and plumbing systems.
  • No Person-to-Person Spread: Unlike many respiratory infections, Legionnaires’ disease does not typically spread between people.
Symptoms of Legionnaires’ Disease

Symptoms usually appear 2 to 10 days after exposure and can range from mild to severe, including:

  • High Fever: Often above 39°C (102°F).
  • Chills and Cough: Persistent cough, which may produce mucus or blood.
  • Shortness of Breath: Difficulty breathing due to lung inflammation.
  • Muscle Aches and Fatigue: Generalized weakness and body pain.
  • Headache and Confusion: Some individuals experience neurological symptoms.
  • Gastrointestinal Issues: Nausea, vomiting, diarrhea, and loss of appetite.
Prevention
  • Water System Maintenance: Regular cleaning and disinfection of cooling towers, hot water tanks, and air-conditioning systems.
  • Temperature Control: Keeping water at proper temperatures (above 60°C for hot water systems and below 20°C for cold water tanks) to prevent bacterial growth.
  • Safe Water Practices: Avoiding stagnant water and regularly flushing unused plumbing systems.
  • Proper Use of Humidifiers and Hot Tubs: Ensuring these devices are regularly cleaned and disinfected.
Treatment of Legionnaires’ Disease
  • Antibiotics: Fluoroquinolones or macrolides (such as levofloxacin or azithromycin) are commonly prescribed.
  • Hospitalization: Severe cases may require oxygen therapy, ventilators, or intensive care.
  • Supportive Care: Includes fluids, fever management, and respiratory support as needed.
  • Early Treatment: Prompt medical attention significantly improves recovery and reduces complications.
Legionnaires’ Disease Around the World

Legionnaires’ disease is a global concern, particularly in hotels, cruise ships, hospitals, and large buildings with complex water systems. According to the **WHO** and **CDC**, outbreaks often occur due to poor water management. The incidence of Legionnaires’ disease has been rising in many countries, making proper water system maintenance critical to public health.

Helpful Resources