17750 Legionnaires Disease

Overview

Legionnaires' disease is a serious type of pneumonia (a lung infection). It is caused by bacteria called Legionella, which live in water. People usually catch it by breathing in small water droplets containing the bacteria. It is not spread from person to person.

It is uncommon. Most people exposed to Legionella bacteria do not become ill. In many countries, only a few hundred to a few thousand cases are reported each year.

Anyone can get it, but it is more likely to affect people over 50, smokers, people with long-term lung conditions, and people with weakened immune systems.

Symptoms

Common symptoms

• High fever (often over 40°C/104°F)
• Cough (may be dry at first, then with mucus)
• Shortness of breath
• Chest pain
• Muscle aches and pain
• Headache
• Tiredness and confusion (especially in older adults)
• Nausea, vomiting, or diarrhea

Causes

Main causes

• Breathing in fine water droplets (aerosols) contaminated with Legionella bacteria from sources such as air-conditioning systems, cooling towers, hot tubs, showers, and decorative fountains.
• Accidentally inhaling infected water into the lungs (aspiration), which can happen during drinking or swallowing problems.
• Travelling and staying in hotels, cruise ships, or hospitals with large water systems that have not been maintained properly.

Risk factors

• Age 50 or older
• Smoking (current or past)
• Chronic lung disease (such as long-term bronchitis or emphysema)
• Weakened immune system (from conditions such as cancer, diabetes, kidney failure, or medications that suppress the immune system)
• Heavy alcohol use
• Recent surgery or a hospital stay
• Being in a building with a complex water system that is not well maintained

When to see a doctor

See a doctor urgently if:

• You have a persistent cough and high fever that is not improving after a few days.
• You are short of breath or are breathing faster than usual.
• You feel very unwell, confused, or are coughing up discolored mucus.
• You have a lung condition and your symptoms are worsening.

Book a routine appointment if:

• You have been in a high-risk environment (such as a hotel, cruise ship, or hospital) and have developed any cough, fever, or flu-like illness.
• You want to discuss your risk of Legionnaires' disease because of travel or environmental exposure.

Diagnosis

Your doctor will ask about your symptoms, recent travel, and any possible contact with water systems. They will listen to your chest. To confirm the diagnosis, they will arrange tests, usually starting with a chest X-ray and a urine test.

Tests that may be done

• Chest X-ray — looks for signs of pneumonia
• Urine test — checks for pieces of Legionella bacteria in your urine
• Sputum (phlegm) sample — tests mucus coughed up from your lungs
• Blood tests — check infection levels and how well your organs are working

What to expect at your appointment

Testing may take a few days. If your doctor strongly suspects Legionnaires' disease, treatment with antibiotics will usually start right away, even before results come back. You may be asked to wait for results at home or in hospital, depending on how ill you are.

Treatment

Legionnaires' disease is treated with antibiotics. The earlier treatment begins, the better. Many people need to be admitted to hospital, especially if they are older, have other health problems, or have severe symptoms. With prompt treatment, most people recover.

Self-care at home

• Rest as much as you can and do not rush back to work or exercise.
• Drink small amounts of water and clear fluids regularly.
• Talk to a pharmacist or GP about safe ways to manage fever and discomfort.
• Avoid smoking and stay away from smoke while your lungs heal.

Medical treatments

Antibiotics are the main treatment. They may be given as tablets or, in hospital, through a drip (intravenously). You may also receive oxygen to help with breathing, and fluids through a drip if you are dehydrated. Your healthcare team will decide the most appropriate antibiotic based on your situation. In severe cases, intensive care may be needed.

Living with this condition

Recovery from Legionnaires' disease can take weeks or even months. You may feel tired, weak, and breathless when active. Allow your body to heal. Go to all follow-up appointments, and contact your GP if your symptoms come back or get worse.

Lifestyle tips

• Pace yourself: break tasks into small steps and rest between them.
• Gradually increase your activity as you feel stronger.
• If you smoke, ask your GP or local health service about quit-smoking support.
• Avoid exposure to smoke and lung irritants.
• Limit alcohol while your body is recovering.

Diet and exercise

Eat a balanced diet with plenty of fruit, vegetables, and protein to help your body recover. Drink enough fluids. When exercising, start gently — for example, a short daily walk — and increase only as you feel able. If you have shortness of breath, stop and rest.

Mental health and emotional wellbeing

Being seriously ill can be scary. You may feel anxious, low, or frustrated during recovery. These feelings are common. Talk to your family, friends, or GP. If you ever feel you cannot cope, or have thoughts of self-harm, contact a crisis helpline or go to your nearest emergency department.

Prevention

The best way to prevent Legionnaires' disease is to maintain water systems properly. This is usually the responsibility of building owners and managers. You can help by cleaning and descaling shower heads and taps, especially after returning from a trip. If you own a building, follow local water safety guidelines.

Complications

If left untreated

• Respiratory failure — the lungs cannot provide enough oxygen to the body
• Sepsis — a life-threatening whole-body reaction to infection
• Kidney failure
• Lung abscess (a pocket of pus in the lung)
• Death in severe cases, especially if treatment is delayed

Long-term outlook

Most people who receive antibiotics early make a full recovery. There may be long-term tiredness or breathing problems, but these often improve over time. For those with serious underlying conditions or delayed treatment, recovery may take longer and require ongoing medical support. The outlook is much better when treatment starts quickly.

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