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Signs and Symptoms

Español: Signos y síntomas

Summarized below are the signs and symptoms for two illnesses caused by Legionella: Legionnaires’ disease and Pontiac fever.

Legionnaires' Disease

Chest x-ray

Legionnaires' disease can be hard to diagnose because its symptoms are similar to other types of pneumonia and it often looks the same on a chest x-ray.

Legionnaires' disease can be hard to diagnose because its symptoms are similar to other types of pneumonia and it often looks the same on a chest x-ray. Specific tests are needed to determine if a case of pneumonia is Legionnaires’ disease.

The most common symptoms of Legionnaires' disease include:

  • Cough
  • Shortness of breath
  • High fever
  • Muscle aches
  • Headaches

These symptoms usually begin 2 to 10 days after being exposed to the bacteria, but it can take longer so people should watch for symptoms for about 2 weeks after exposure.


Pontiac Fever

Pontiac fever has many of the same symptoms as Legionnaires’ disease, primarily fever and muscle aches, but it is a milder infection. Symptoms begin between a few hours to 3 days after being exposed to the bacteria and usually last less than a week. Pontiac fever is different from Legionnaires' disease because someone with Pontiac fever does not have pneumonia.


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