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

Legionnaires' disease is a serious lung infection (pneumonia) caused by Legionella bacteria. While the bacteria are found naturally in freshwater environments, they can become a significant health risk when they colonise man-made water systems. For UK residents travelling abroad, the risk often arises from contaminated air conditioning units, hot tubs, whirlpool baths, or large plumbing systems in hotels and resorts.

The infection is not contagious; you cannot catch it from another person or by drinking contaminated water. Instead, it is contracted by inhaling aerosolised water droplets—essentially a fine mist—that carries the bacteria deep into the lungs. Because the symptoms mirror common respiratory issues, it is frequently overlooked during the early stages of illness.

Symptoms of Legionnaires' disease usually develop between 2 to 10 days after exposure, though it can take up to two weeks in some cases. According to NHS and NICE guidance, the clinical presentation often begins with flu-like symptoms that rapidly progress into a more severe lower respiratory tract infection.

Early Signs

• High fever (often above 38°C) and chills.
• Muscle aches and general malaise.
• A persistent headache.

Progressive Symptoms

As the infection takes hold in the lungs, you may experience:

• A persistent dry cough, which may later produce phlegm or occasionally blood.
• Shortness of breath or pain when breathing.
• Gastrointestinal symptoms such as nausea, vomiting, or diarrhoea.
• Mental confusion or disorientation, particularly in older travellers.

While any traveller can contract Legionnaires' disease, certain groups are at a higher risk of developing a severe illness. Public Health England (PHE) data suggests that middle-aged and older adults, particularly those over the age of 50, are more vulnerable. Other risk factors include being a current or former smoker, having a chronic lung condition like COPD, or having a weakened immune system due to medication or underlying health conditions like diabetes.

Hotels and holiday rentals that have been vacant for some time are common sources of outbreaks. If water sits stagnant in pipes during low season, the bacteria can multiply to dangerous levels. When a guest arrives and turns on the shower, the initial mist can be highly concentrated with Legionella.

Prevention is the most effective way to manage travel-related health risks. When checking into holiday accommodation, there are several practical steps you can take to reduce your exposure to Legionella bacteria:

• Flush the system: If the room feels like it hasn't been used recently, run all taps and showers on the hottest setting for at least two or three minutes. It is best to leave the room or hold your breath and keep the door closed while doing this to avoid inhaling the initial spray.
• Monitor Hot Tubs: Only use hot tubs or whirlpools that appear well-maintained and have clear, chemically treated water. If the water looks cloudy or the facility feels unhygienic, avoid it.
• Air Conditioning: Ensure air conditioning units in your accommodation are well-maintained. If a unit is leaking or smells musty, report it to the management immediately.

If you return to the UK and feel unwell with a fever and cough, it is vital to mention your recent travel history to a healthcare professional. Legionnaires' disease is diagnosed through specialised tests, such as a urinary antigen test or a sputum culture, which are more specific than a standard chest X-ray.

In line with NICE guidelines, the primary treatment for Legionnaires' disease is a course of antibiotics. Macrolides (such as clarithromycin) or fluoroquinolones are typically used because they can penetrate the lung cells where the bacteria hide. Most patients require 1 to 3 weeks of treatment. Severe cases may require hospitalisation for intravenous fluids and oxygen support, which is why early intervention is so critical.

If you have recently returned from a holiday and are experiencing lingering flu-like symptoms, persistent muscle aches, or a new cough, you can speak to a GP online for an initial assessment. An online consultation is a convenient way to discuss your travel history and symptoms without leaving your home.

A UK online doctor can help differentiate between a common cold, COVID-19, and more serious travel-related infections. They can provide clinical advice on your symptoms and, if Legionnaires' disease is suspected, they will direct you to the appropriate local NHS services for urgent testing and physical examination. Providing a detailed timeline of your holiday and any specific exposures (like using a hotel spa) will help the doctor provide the most accurate guidance.