Legionnaires’ disease

Legionnaires’ disease is an uncommon but potentially serious form of pneumonia caused by an infection.

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What is Legionnaires’ disease?

Legionnaires’ disease is an uncommon but potentially serious form of pneumonia. You can become infected if you breathe in droplets of water from a contaminated water source, such as:

  • air conditioning systems
  • spa pools and hot tubs
  • showers and taps
  • cooling towers
  • nebulisers and humidifiers (if topped up with contaminated tap water)
  • decorative water fountains.

You can read more about potential sources of Legionnaires’ disease on the Health and Safety Executive website.

You are very unlikely to catch Legionnaires’ disease from:

  • ponds, lakes and rivers
  • drinking water with the bacteria in it
  • other people with the infection.

About 3 in 10 cases of Legionnaires’ disease are contracted abroad, so always mention any recent foreign travel when you see your doctor and you’re unwell.

Who is at risk of Legionnaires’ disease?

Anyone can develop Legionnaires’ disease. But you’re more likely to be seriously ill if:

  • you have a long-term lung condition like asthma or chronic obstructive pulmonary disease (COPD)
  • you have a long-term condition that affects your heart, kidneys, or other major organs
  • you smoke
  • you’re over 45
  • you’re addicted to alcohol or drugs
  • you have problems with your immune system.

What are the symptoms of Legionnaires’ disease?

If you have Legionnaires’ disease, you’ll have symptoms similar to pneumonia, flu or a chest infection. These symptoms can include:

  • coughing
  • a high temperature
  • difficulty breathing
  • chest pain or discomfort.

More severe cases of Legionnaires’ disease may also cause:

  • feeling and being sick
  • diarrhoea
  • confusion.

The period of time between breathing in the bacteria and developing symptoms (called the incubation period) is normally 2 – 10 days. However, it can take up to two weeks. Symptoms can develop quickly, as the infection spreads across your lungs.

If you have the following severe symptoms, get urgent advice. Call 111 or 999 if:
  • you have a high temperature
  • you feel like you have severe flu
  • you have severe chest pain and can’t breathe properly.

How is Legionnaires’ disease treated?

If you have Legionnaires’ disease, the sooner you get treatment, the better. Most people with Legionnaires’ disease are admitted to hospital and you may:

  • be given antibiotics directly in a vein
  • be given oxygen therapy
  • be looked after in intensive care and have a machine to help you breathe (mechanical ventilation) if you have a severe case.

When you start to feel better, you may need to continue to take antibiotic tablets at home. Antibiotic treatment usually lasts 1 to 3 weeks. You’re likely to make a full recovery and feel back to normal after a few weeks.

Reporting Legionnaires’ disease

If you get Legionnaires’ disease, you can report it on the government website. This will help local authorities to reduce the risk of Legionnaires’ disease.

What’s the outlook of Legionnaires’ disease?

The quicker you’re diagnosed and treated, the better the outcome for Legionnaires’ disease. But Legionnaires’ disease is a serious form of pneumonia. It’s thought that even in previously healthy people, there’s a 1 in 10 chance of dying if you get Legionnaire’s disease. This becomes higher if you have a risk factor for significant illness from Legionnaires’ disease.

If you catch Legionnaires’ disease abroad, in the workplace, in rented accommodation, or somewhere else in the UK, you may be entitled to legal aid and support. Give our Helpline a call on 0300 222 5800 to discuss your options.

How can Legionnaires’ disease be prevented?

At home

Good upkeep of water systems is important to preventing Legionnaires’ disease. You can reduce the risk of Legionnaires’ disease at home by removing any build-up around shower heads, as this can trap water. If you have showers or taps you haven’t used recently, flush them by opening the tap and letting the water run for five minutes every two weeks.

If you have a home spa or hot tub, it’s essential to regularly drain, clean and disinfect it. Follow the manufacturer’s instructions and use the recommended products.

If you rent your home, your landlord has a legal duty to make sure all water systems in their homes are properly maintained. Regulations and guidance are issued by the Health & Safety Executive UK. You can contact the charity Shelter for more advice and support about landlords.

At work

Employers have a legal duty to make sure all water systems in their premises are properly maintained. Regulations and guidance are issued by the Health & Safety Executive UK.

If you have concerns about air conditioning or water systems at work, you should ask your office manager if the systems are checked regularly. You can also ask your health and safety rep or your union rep if you have one.

While travelling

If you’re going somewhere in Europe, you can check if there have been any recent cases of Legionnaires’ disease on the ECDC website.

You can also flush out any showers and taps at hotels or other types of shared accommodation by running hot water through them for five minutes before you use them.

Did you find this information useful?

We use your comments to improve our information. We cannot reply to comments left on this form. If you have health concerns or need clinical advice, call our helpline on 0300 222 5800 between 9am and 5pm on a weekday or email them.

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