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

Legionnaires' disease is a serious lung infection (pneumonia) caused by the Legionella bacterium. While most healthy people who are exposed to the bacteria do not become ill, it can cause severe respiratory distress in vulnerable individuals. According to the NHS and Public Health England, the condition is relatively rare but can be life-threatening if not treated promptly with appropriate antibiotics.

The bacteria thrive in warm water environments, typically between 20°C and 45°C. In nature, they are found in ponds and rivers in low concentrations, but they become a health risk when they colonise man-made water systems such as cooling towers, hot tubs, and large plumbing systems often found in hotels and holiday resorts.

When travelling abroad, particularly to warmer climates, British holidaymakers may be at higher risk due to poorly maintained water systems. The Legionella bacteria spread through aerosolised water—fine mists that are easily inhaled into the lungs.

• Hotel Showers and Taps: If a room has been vacant for several days, water sitting in the pipes can become stagnant and warm, allowing bacteria to multiply.
• Hot Tubs and Whirlpools: These are notorious for maintaining the exact temperature bacteria prefer. If the chlorine or bromine levels are not strictly managed, they can become breeding grounds.
• Air Conditioning Units: Large central air conditioning systems that use cooling towers can disperse contaminated mist over wide areas.
• Decorative Fountains: Mist from fountains in hotel lobbies or public squares can also be a source of infection.

The symptoms of Legionnaires' disease often mimic other types of pneumonia or even severe influenza, making it difficult to distinguish without medical testing. The incubation period—the time from breathing in the bacteria to feeling ill—is usually 2 to 10 days, though it can take up to two weeks.

Early Signs

Patients typically start with a 'flu-like' illness, experiencing muscle aches, tiredness, and a significant headache. A high temperature (fever) of 38°C or above is very common, often accompanied by chills.

Respiratory Symptoms

As the infection settles in the lungs, you may develop a persistent cough, which can be dry or produce phlegm (sometimes containing blood). Shortness of breath and chest pain when breathing are also key indicators. In some cases, patients also report gastrointestinal issues like nausea, vomiting, or diarrhoea, alongside confusion or mental changes.

If you return to the UK from a holiday and feel unwell with respiratory symptoms, it is essential to mention your travel history to a healthcare professional. NICE guidelines suggest that Legionnaires' disease should be considered in any patient with community-acquired pneumonia who has recently travelled.

Diagnosis is usually confirmed through a urine test that looks for Legionella antigens or via a phlegm sample. Once diagnosed, the treatment involves a course of specific antibiotics, such as macrolides or fluoroquinolones. Most patients require hospital admission to receive intravenous fluids and oxygen support to help the lungs recover.

While you cannot control a hotel’s maintenance schedule, there are steps you can take to reduce your personal risk:

• Flush the system: Upon arriving at your hotel, run the shower and all taps for several minutes. It is best to leave the room while doing this to avoid breathing in any initial mist.
• Check hot tub hygiene: Only use whirlpools that appear clean and have a strong smell of disinfectant. If the water looks cloudy, avoid it.
• Stay hydrated: While this doesn't prevent the infection, it supports your general immune health.
• Be aware of your risk: If you are over 50, a smoker, or have chronic lung disease, you should be extra vigilant about respiratory symptoms after travel.

If you have recently returned from abroad and have developed a cough or a fever, you may be worried about your health. Choosing to speak to a GP online in the UK is an excellent first step for a clinical assessment from the comfort of your home.

An online doctor can review your symptoms, discuss your travel history, and provide advice on the next steps. They can help determine if your symptoms are likely a common cold or if they warrant an urgent face-to-face appointment or hospital referral. If you are feeling generally unwell but are not in respiratory distress, a virtual consultation provides a calm, evidence-based environment to address your concerns and receive a sick note if required for your recovery.