Signs and Symptoms

People who get sick after being exposed to Legionella can develop two different illnesses, collectively known as legionellosis: Legionnaires’ disease and Pontiac fever.

Legionnaires’ Disease

Legionnaires’ disease is very similar to other types of pneumonia (lung infection), with symptoms that include:

Chest x-ray

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

  • Cough
  • Shortness of breath
  • Fever
  • Muscle aches
  • Headaches

Legionnaires’ disease can also be associated with other symptoms such as diarrhea, nausea, and confusion. Symptoms usually begin 2 to 14 days after being exposed to the bacteria, but it can take longer.

If you develop pneumonia symptoms, see a doctor right away. Be sure to mention if you may have been exposed to Legionella, have used a hot tub, spent any nights away from home, or stayed in a hospital in the last two weeks.

Pontiac Fever

Pontiac fever is a milder infection than Legionnaires’ disease. Symptoms are primarily fever and muscle aches. Symptoms can 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.