Legionella | Health & Senior Services

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What is Legionella?

Picture showing the life cycle of biofilms

Legionella is a type of bacteria that can't be seen with a regular microscope, are rod-shaped, and “Gram-negative” (stain pink or red when prepared for viewing under a special microscope). It needs oxygen to survive ("aerobic") and lives inside other cells ("intracellular"). There are many different types of this bacteria, called "serogroups" – over 15 in total.
You can find Legionella bacteria in freshwater like lakes and rivers. They often live inside tiny single-celled organisms called "protozoa." This is where they hang out and multiply.
Legionella bacteria can stick together with other bacteria to form "biofilms." These are like slimy layers that protect the bacteria. Biofilms make it hard to kill Legionella with antibiotics, chlorine (like in swimming pools), or even high temperatures.

How does Legionella get into our drinking water systems?

Legionella lives in many natural water sources like lakes, streams and rivers.

When we take water from these places to use in our homes and buildings, Legionella can sometimes come along with it.

Even if your water is treated, it might not completely get rid of Legionella. While public water utilities must provide safe drinking water; tap water is not sterile, meaning it might have germs in it. Small amounts of this bacteria can slip through the system and end up in your pipes.

When nearby construction (jackhammering) and problems like breaks, leaks or flooding damage the pipes, dirt and bacteria/germs can also get into the water

Picture of a showerhead with mineral buildup

Legionella grows best in water that is warm, between 68- and 122-°F.

When the water is too hot or too cold, the bacteria cannot grow as well.

However, many buildings keep their water at just the right temperature for Legionella to thrive.

This can lead to the bacteria growing in your pipes and coming out of faucets, showerheads and other water outlets.

How can Legionella affect me?

When water from these places turns into tiny droplets or mist, it can carry Legionella germs. If you breathe in (inhale) these droplets, you might get sick.

The main way people get infected with Legionella is by breathing in tiny water droplets that contain the bacteria. These droplets can come from things like mist from power washers, fountains, hot tubs, or showerheads.
Once inside the body, the bacteria are eaten by special cells called "macrophages." These cells are supposed to kill bacteria, but Legionella is tricky. It can create a protective shell around itself inside the macrophage, which protects it from being destroyed. (1)

Who is at risk for Legionellosis?

While most healthy people won't get sick from it, Legionella can cause serious illness for people over 50, with lung issues, or conditions that weaken the immune system. Legionellosis, the illness caused by legionella, can lead to pneumonia, and has a 10-25 percent fatality rate for those who are affected.

A graphic of the symptoms of Legionellosis

Graphic of the human body with arrows to locations of symptoms of legionellosis.

Signs and Symptoms of Legionellosis:

Flu-like illness: Cough, high fever, muscle aches, tiredness, headache and malaise
Respiratory symptoms: Shortness of breath, chest pain and chest discomfort
Gastrointestinal symptoms: Diarrhea, nausea and vomiting
Mental changes: Confusion, disorientation and balance problems
Other symptoms: Excessive sweating, loss of appetite and stomach pain

To learn more visit: https://www.cdc.gov/drinking-water/prevention/preventing-waterborne-germs-at-home.html