Legionnaires' Disease & Travel: Symptoms, Prevention and UK Advice

Legionnaires' disease is a potentially serious lung infection (pneumonia) caused by Legionella bacteria. While these bacteria occur naturally in fresh water, they can multiply to dangerous levels in man-made water systems such as hotel plumbing, air conditioning units, and hot tubs. According to NHS guidance, it is not contagious; you cannot catch it from drinking contaminated water or from another person. Instead, it is contracted by inhaling aerosolised droplets—tiny mists of water—that contain the bacteria.

For UK travellers, the risk often increases when visiting destinations where water regulations may be less stringent or when staying in accommodation that has been vacant for some time, allowing water to stagnate in the pipes. Understanding the risks associated with travel is the first step in ensuring a safe return home.

The symptoms of Legionnaires' disease usually develop between 2 to 10 days after exposure, though in some cases, it can take up to two weeks. Initially, the illness may feel like a severe case of the flu. Patients often report:

• A high temperature (fever), chills, and sweating.
• A persistent cough, which may be dry or productive of phlegm.
• Shortness of breath or sharp chest pains when breathing.
• Muscle aches and tiredness.
• Confusion or headaches.

In some instances, the bacteria can cause a milder illness known as Pontiac fever, which involves flu-like symptoms but does not lead to pneumonia. However, because Legionnaires' can be fatal if left untreated—particularly in those over 50, smokers, or individuals with weakened immune systems—any respiratory symptoms following a holiday should be treated with caution.

Certain environments common to holidaymakers are known ‘hotspots’ for Legionella. When you speak to a GP online about travel health, they may highlight the following risks:

Hotel Water Systems

Showers and taps that have not been used recently can harbour stagnant water where bacteria thrive. Large hotels with complex plumbing and old cooling towers are historically linked to outbreaks.

Spa Pools and Hot Tubs

Warm, aerated water provides the perfect incubation temperature for Legionella. If pools are not correctly chlorinated or filtered, the bubbles created by jets can carry the bacteria directly into your lungs.

Air Conditioning

While modern split-level air conditioning units in homes are generally safe, large-scale industrial cooling systems used in some resorts have been known to spread contaminated mist over wide areas.

Prevention is key to travel safety. NICE and Public Health authorities suggest several practical steps to reduce your risk when staying in holiday accommodation abroad:

• Flush the system: Upon arrival at a holiday rental or hotel room, run all showers and taps at the hottest setting for several minutes. Leave the room and close the door while doing this to avoid breathing in the steam.
• Inspect Spa Facilities: Only use hot tubs and pools that appear clean and well-maintained. If the water looks cloudy or the facility smells unusual, avoid it.
• Humidifiers: Use only boiled or distilled water in CPAP machines or humidifiers while travelling, as tap water may contain low levels of bacteria.
• Travel Advice: If you are travelling to an area with known poor water infrastructure, consult an online doctor UK service before your trip for a full travel health risk assessment.

If you return to the UK and suspect you have contracted Legionnaires' disease, diagnosis usually involves a urine test or a sample of phlegm to look for the bacteria. Doctors may also use a chest X-ray to confirm the presence of pneumonia. Treatment typically involves a course of intravenous or oral antibiotics, such as macrolides or fluoroquinolones, as per NICE clinical guidelines.

While mild respiratory infections can sometimes be managed at home, Legionnaires' disease often requires a hospital stay to ensure the patient receives adequate oxygen and fluids. If you are feeling generally unwell but are not in respiratory distress, an online GP can help determine whether your symptoms warrant an immediate referral to secondary care.

An online GP service is an excellent resource for pre-travel planning and post-travel symptom checking. You should book a consultation if:

• You are planning a trip and want to discuss travel health advice UK specific to your destination and underlying health conditions.
• You have returned from a holiday within the last fortnight and have developed a mild cough or fever.
• You have concerns about the safety of facilities you used while abroad.
• You require a referral or a sick note for work due to ongoing fatigue following a respiratory illness.

An online GP can review your travel history, assess your symptoms via video link, and provide evidence-based guidance on the next steps, ensuring you receive the correct care without unnecessary delay.