Legionnaires’ Disease Facts

Legionnaires’ disease is caused by the waterborne Legionella bacteria, named after the 1976 outbreak involving a Philadelphia convention of the American Legion. During the event, many veterans and some attendees developed a severe, previously unrecognized form of pneumonia that became known as Legionnaires’ disease. The Centers for Disease Control and Prevention estimates approximately 8,000 cases of Legionnaires’ disease annually. Peer-reviewed literature suggests that building drinking water systems are the primary pathways for exposure to Legionella bacteria (+) which originates in fresh and municipal water systems.

The Symptoms

Possible Pathways to exposure

Faucets Hot Tubs & Pools Showers & Baths Humidifiers Fountains Pipes Drinking Water Cooling Equipment

Who’s At Risk

While smokers, the elderly, and those with asthma,
chronic lung disease or suppressed immune systems are more
likely to become infected healthy people may also be at risk.

InvestigatingAn Outbreak

Whether it’s a single case or a larger outbreak, it is important to thoroughly investigate each instance of Legionnaires’ disease to reduce the risk of further cases. The CDC offers comprehensive investigation protocols to accurately confirm cases and identify the source of exposure so the affected area of a water system can be treated. Such protocols should be used in their entirety to accurately identify the cause and prevent future cases. Find information here and here.

How it’sTransmitted

Legionnaires’ disease is caused by inhaling or aspirating small droplets of water contaminated with Legionella bacteria.

FALSE		THE FACTS
Legionnaires’ disease most often occurs in large outbreaks.	}	Only 4% of Legionnaires’ disease cases are part of known outbreaks. There are approximately 5,000 cases per year in the United States.
The primary cause of Legionnaires’ disease is cooling towers.	}	Peer-reviewed studies published in the New England Journal of Medicine, The Lancet: Infectious Diseases, and many other publications have found the drinking water supply to be the primary source of the bacteria.
You can’t get Legionnaires’ disease from a shower head.	}	Bacteria can grow in the plumbing and in the shower head, which breaks up the water into a fine mist which can easily be inhaled allowing bacteria to travel directly to the lungs.