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175 Healthcare: Biological Hazards
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How Legionellosis Spreads

After Legionella grows and multiplies in a building water system, water containing the bacteria spreads as droplets small enough for people to breathe in.

People can be infected by Legionella bacteria when they breathe in small droplets of water contaminated with the bacteria. Less commonly, people can get sick by aspiration of drinking water containing Legionella. This happens when water accidentally goes into the lungs while drinking. People at increased risk for aspiration include those with swallowing difficulties.

People at Increased Risk

Most healthy people exposed to Legionella do not get sick. People at increased risk of getting sick are:

  • people 50 years or older
  • current or former smokers
  • people with a chronic lung disease (like chronic obstructive pulmonary disease or emphysema)
  • people with weak immune systems or who take drugs that weaken the immune system (like after a transplant operation or chemotherapy)
  • people with cancer
  • people with underlying illnesses such as diabetes, kidney failure, or liver failure
Most healthy people exposed to Legionella do not get sick.

Symptoms

Common symptoms of a Legionella infection include:

  • dry cough
  • high fever
  • chills
  • muscle aches
  • diarrhea
  • fatigue
  • headache
  • abdominal pain
There are a lot of symptoms for people with Legionnaires' disease.

Legionella bacterial infections are usually treated with Erythromycin or a combination of Erythromycin and Rifampin. There are no vaccines that can prevent Legionnaires’ disease.

Knowledge Check Choose the best answer for the question.

1-2. Which of the following is a common symptom of a Legionella infection?