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Legionnaires' disease is a type of pneumonia. It is caused by bacteria called Legionella pneumophila. The bacteria got its name in 1976, when a group of people attending an American Legion convention became infected. Although it was present before 1976, Legionnaires' disease is being diagnosed more often now as doctors look for Legionella bacteria in people who have pneumonia. You can get Legionnaire's disease at any time of the year, but more cases are usually found in the summer and early fall. While Legionnaires' disease can be very serious, most cases can be treated successfully.
The Legionella pneumophila bacteria can also cause a less severe, flu-like condition known as Pontiac fever.
People usually get Legionnaires' disease or Pontiac fever when they breathe in a mist or vapour (small droplets of water in the air) that contains the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected. Other sources include fountains and water sources in hotels, cruise ships, nursing homes, and hospitals.
These diseases aren't contagious. The bacteria are not spread from one person to another person. You can get the diseases again if you are exposed to the bacteria again.
The most common symptoms of Legionnaires' disease include:
Less common symptoms range from muscle aches and headaches to abdominal (belly) pain, shortness of breath, and chest pain.
Legionnaires' disease symptoms usually appear 2 days to 2 weeks after a person is exposed to the bacteria. Symptoms can range from mild to severe.
Pontiac fever symptoms include fever and muscle aches. Symptoms usually appear 1 to 2 days after a person is exposed to the bacteria. They usually go away without treatment in a few days.
Your doctor can diagnose both Legionnaires' disease and Pontiac fever by asking about your past health and by doing a physical exam. If your doctor thinks you have Legionnaires' disease, the doctor will ask about your working conditions, if you have been around any possible source like fountains or hot tubs, and if you have travelled within the past 2 weeks. The doctor will also do tests. The tests may include a chest X-ray, blood test, urine test, or looking at mucus from your lungs.
Most cases of Legionnaires' disease can be treated successfully with antibiotics. Treatment usually lasts at least 5 days.
Fever tends to improve or go away within the first few days. A cough may take longer to disappear. But in general you should start to feel better within the first few days of treatment. Complete recovery can take from 2 to 4 months.
Pontiac fever will go away without treatment. To reduce fever and muscle aches, drink plenty of fluids and consider taking over-the-counter pain relievers like acetaminophen (Tylenol, for example) or non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDs include ibuprofen (such as Advil and Motrin), naproxen (such as Aleve), and aspirin. Do not give aspirin to anyone younger than 18 because of the risk of Reye syndrome. Be safe with medicines. Read and follow all instructions on the label.
Most people who are exposed to the bacteria don't become ill. But if you believe you were exposed, talk to your doctor or local health unit. Be sure to tell them where you think you were exposed and if you have travelled in the last 2 weeks. This information will help them correctly diagnose and treat the disease, locate the source of the bacteria, and prevent others from being exposed to it.
Current as of: October 31, 2022
Author: Healthwise StaffClinical Review Board: E. Gregory Thompson MD - Internal MedicineAdam Husney MD - Family MedicineElizabeth T. Russo MD - Internal Medicine
Current as of: October 31, 2022
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Adam Husney MD - Family Medicine & Elizabeth T. Russo MD - Internal Medicine
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