Daijiworld Media Network- Mumbai

Mumbai, Aug 8: Most people may never have heard of Legionella pneumophila, yet this tiny bacterium has been behind several deadly outbreaks of a severe form of pneumonia known as Legionnaires’ disease. The illness, which affects the lungs and can be life-threatening, especially for the elderly, smokers, and those with weakened immune systems, is more common than many realise.

The bacteria thrive in warm, stagnant water, often found in hot tubs, fountains, plumbing systems, and—of particular concern—large industrial air conditioning units such as those used in hotels, hospitals, shopping centres, and office complexes.

How Air Conditioners Can Spread the Disease

Large AC systems with cooling towers or water tanks can provide ideal breeding grounds for Legionella if not cleaned and maintained regularly. When contaminated water inside these systems turns into microscopic droplets, they can be dispersed into the air through vents. Breathing in these droplets can lead to infection.

The illness is not contagious from person to person but can strike anyone who happens to be in a building with a poorly maintained HVAC system. The most famous outbreak occurred in 1976 at an American Legion convention in Philadelphia, where over 200 people were infected and 29 died, all traced back to a hotel’s air conditioning system.

Recognising the Symptoms

Legionnaires’ disease symptoms usually appear 2–10 days after exposure. Initial signs resemble flu—fever, chills, headaches—before progressing to shortness of breath, chest pain, cough with mucus, and severe fatigue. Prompt medical attention is crucial, as early treatment with antibiotics can prevent serious complications.

Prevention is the Best Defence

While household AC units are generally not a concern, large-scale systems must be properly maintained. Key preventive measures include:

• Regular cleaning and servicing of AC systems

• Flushing unused water systems

• Using biocides or chemical treatments in cooling towers

• Preventing stagnant water build-up in HVAC systems

Travellers are also advised to be cautious—if a hotel’s air feels musty or unusual, it could be a sign of poor maintenance.

Though not widespread, Legionnaires’ disease remains a serious, preventable illness. Regular upkeep of cooling systems is essential to ensure public safety, especially in high-traffic buildings.