Legionnaires' Disease: Symptoms, Transmission & Treatment

Legionnaires' disease is a severe lung infection caused by the Legionella pneumophila bacteria. It leads to a serious form of bacterial pneumonia, with symptoms such as shortness of breath, difficulty breathing, fever, chest pain, and muscle aches.

This infection is transmitted by inhaling airborne water droplets containing the bacteria. Legionella pneumophila thrives in warm, moist environments like hot tubs and air conditioning systems.

Treatment for Legionnaires' disease should be managed by a pulmonologist and typically involves antibiotics. In more severe cases, hospitalization and oxygen therapy may be needed, depending on symptom severity.

Main symptoms

The most common symptoms of Legionnaires' disease include:

• Chest pain

• High fever

• Dry cough, which may contain blood

• Difficulty breathing and shortness of breath

• Chills

• General discomfort or fatigue

• Headache

• Vomiting, abdominal pain, and diarrhea

Symptoms can appear up to 10 days after exposure to the bacteria. If signs of infection are present, it is important to consult a pulmonologist or general practitioner to confirm the diagnosis and begin appropriate treatment. Early medical care helps prevent serious complications like respiratory failure.

What Legionella causes

Legionella pneumophila causes a severe type of bacterial pneumonia. It is one of the leading causes of community-acquired or hospital-acquired pneumonia.

Confirming a diagnosis

Diagnosis of Legionnaires' disease is made by a pulmonologist, general practitioner, or infectious disease specialist. It involves evaluating symptoms, reviewing medical history, and performing a physical exam, including listening to the lungs with a stethoscope.

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To confirm the diagnosis, the doctor may also order tests such as a chest X-ray, sputum culture, and a complete blood count. These help assess lung function, overall health, and detect the presence of Legionella pneumophila.

How it is transmitted

Legionella pneumophila spreads through inhaling aerosolized water particles containing the bacteria. Once inhaled, the bacteria can settle and multiply in the respiratory system, leading to infection.

The bacteria grows easily in warm, humid environments, and can be found in:

• Stagnant water, especially where algae or moss are present

• Dirty water tanks

• Puddles or standing water

• Damp soil

• Air conditioning systems or filters

• Humidifiers

• Vaporizers

• Saunas or spas

Although inhalation is the most common transmission route, infection can also occur by swimming in contaminated rivers, lakes, or pools.

Anyone can be affected by this infection, but it is more common in older adults, smokers, or people with weakened immune systems due to chronic illnesses such as emphysema, asthma, diabetes, or liver failure.

Treatment options

Treatment for Legionella pneumophila infection must be guided by a pulmonologist, general practitioner, or infectious disease specialist, and will vary depending on the severity of symptoms.

In most cases, hospital care is needed, where the doctor may recommend antibiotics, IV fluids, and oxygen therapy to support breathing.

Commonly prescribed antibiotics for Legionnaires' disease include ciprofloxacin, azithromycin, levofloxacin, and erythromycin. Treatment usually lasts 7 to 10 days. The length of hospital stay depends on how well the person responds to treatment.

Some cases resolve within 10 days, but recovery may take longer in people who are older, smoke, have other respiratory diseases, or have weakened immune systems.

How to prevent

To help prevent Legionella pneumophila infection, the following precautions are recommended:

• Avoid taking very hot showers or baths, especially in public places like gyms or hotels

• Do not use hot tubs or spas that haven’t been cleaned in a long time

• When using a bathtub, turn on the water slowly to reduce spray pressure

• Clean air conditioning filters and drip trays with water and chlorine every 6 months

• Soak showerheads in a chlorine solution to disinfect them

• Clean water tanks regularly as needed

These precautions are especially important during a Legionella outbreak, but it is also essential to avoid stagnant water and regularly disinfect household water systems.