Legionnaire’s Disease – The Risk of Dirty Ductwork

Legionnaire’s disease can have dire consequences. In Philadelphia, USA, in 1976, a convention of the American Legion met at the Bellevue-Stratford Hotel with more than 2,000 attendees. Weeks later, tens had died suddenly and more than a hundred more had been hospitalised.

This was the first recorded outbreak of what is now known as Legionnaire’s disease, a bacterial infection which results in the inflammation of the lungs and a range of flu-like symptoms.

What is Legionnaire’s disease?

Legionnaire’s disease is a bacterial infection of the lungs caused by the inhalation of any form of Legionella bacteria. Once infected, sufferers will develop a range of symptoms including muscle pains, headaches, fever and a dry cough which becomes phlegmy with time.

While most people are treated successfully and recover relatively quickly, it can cause lasting complications if left untreated.

In addition to the early symptoms, it can develop into a range of increasingly severe symptoms including nausea, vomiting, diarrhoea and abdominal pain.

What causes Legionnaire’s disease?

Legionnaire’s disease is caused by the inhalation of water vapour containing the Legionella bacteria.

This can happen in a number of ways, with potential sources including:

  • Showers and taps
  • Household plumbing
  • Cooling systems
  • Coldwater systems
  • Spa baths & hot tubs
  • Thermal spas & pools
  • Ornamental fountains
  • Hot water systems
  • Humidifiers
  • Potting compost

The Legionella bacteria themselves can develop in any water where there are sufficient nutrients, but Legionnaire’s disease requires the bacteria to be inhaled, drinking infected water is likely not to result in infection.

Water can become nutrient-rich if it is allowed to become stagnant for too long in pipe networks or containers, where it develops films and collects rust.

In the case of the very first outbreak in 1976, the hotel’s ventilation system was to blame, having recirculated infected vapour through a dirty system.

Unclean and ill-maintained ductwork and ventilation systems can provide the ideal breeding grounds for bacteria, which is then imparted onto passing moisture and spread.


To learn more about ensuring your ductwork and ventilation operates as it should, contact Ductbusters today.

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