• Online training login
t: 0330 223 36 86     e: [email protected]
Legionella Control International
  • Home
  • Services
  • Knowledge
  • Legionnaires
  • About
  • Contact
  • Click to open the search input field Click to open the search input field Search
  • Menu Menu
You are here: / Home / Knowledge / Guidance / Recognising the Symptoms of Legionnaires Disease

What are the Symptoms of Legionnaires’ Disease?

Symptoms of Legionnaires DiseaseBefore the notorious outbreak of Legionnaires’ disease in Philadelphia, USA in 1976, which ultimately led to the discovery of the Legionella bacterium, no one knew what caused the illness that led to the severe pneumonia-like infection that can cause death in the worst-case scenario.

Today however, we have a much better understanding of Legionella bacteria, how they spread and develop, and how they affect people and can potentially make them ill. It can sometimes be difficult to diagnose Legionnaires’ disease to start with, mainly because many of the symptoms are also indicative of influenza or flu.

What are the Symptoms of Legionnaires’ Disease?

So, what are the symptoms? Someone suffering from Legionnaires’ disease is likely to feel feverish and tired in the early stages. They may also suffer muscle aches and pains and get headaches.

As you can see, all these symptoms are also very similar to those of the flu. However, as the infection progresses, it will start to affect the lungs. Since the Legionella bacterium infection causes symptoms like those of pneumonia, anyone affected can expect to develop a cough, shortness of breath and pains in the chest. At this stage, it is vital to seek medical help quickly.

Infection from contaminated aerosols

While legionella cannot be spread from one person to another, it can be caught if mist in the air, referred to as an aerosol, has become contaminated and is then inhaled by someone. Think of the wet spray from a shower, for example, or mist coming out of cooling towers. These are both situations where legionella can easily develop and spread if the maintenance, cleaning, disinfection and sterilisation procedures in place are not good enough to keep bacteria numbers within the control limits set by the Health & Safety Executive (HSE) in their ACOP L8 document.

  • How to test water for Legionella bacteria

How long before symptoms of the disease develop?

The usual incubation time for someone inhaling infected water droplets and developing the first symptoms of the disease is about a week. However, some people fall ill just two or three days later, while for others it might be almost three weeks before they experience symptoms.

Identifying to source of the infection

Using this timeline can help identify the source of the infection when someone has been confirmed to have contracted Legionnaires’ disease. This is important, because the source of the infection must be found so it can be dealt with effectively and so prevent others from falling ill.
Oftentimes, there are clusters of cases that occur and these can help make it easier to identify the common link between them all. In doing so, the source of contamination can be identified and dealt with so no one else falls ill.

Knowing the symptoms of Legionnaires’ disease is very important, particularly if you live or work near cooling towers or use other water-based facilities that could potentially be prone to contamination by Legionella bacteria.

Legionnaires’ risk assessment

    • Do you need a Legionnaires assessment?

Expert legionella risk management support

To find out more about our specialist legionella risk management services including litigation support, legionella risk assessments, City & Guilds training, legionella testing, and other risk management support services call us today on 0330 223 36 86 or get in touch here … contact us

London Office
Kemp House
152 City Road
London EC1V 2NX
United Kingdom
Tel: +44 (0) 203 637 47 48

Manchester Office
Warren Bruce Court
Warren Bruce Road
Manchester M17 ILB
United Kingdom
Tel: +44 (0) 161 877 0586

Further reading

For additional information about Legionella bacteria and Legionnaires’ disease … here

Search Search

Expert resources…

  • Legionella & other pathogens
  • Regulatory compliance
  • Expert guidance
  • International
  • Legionnaires’ disease
  • Legionella training
  • Glossary of terms
  • FAQ
  • News

REVIEWS

4.8
Legionella Control International is rated 4.8 out of 5 stars (based on 182 customer reviews)
Read our reviews

Get in touch...

Legionella Control International
Warren Bruce Court
Warren Bruce Road
Manchester M17 1LB
United Kingdom

Manchester: +44 (0) 161 877 05 86
London: +44 (0) 203 637 47 48
Email: [email protected]

Legionella newsletter...

A simple and convenient way of keeping up to date with the latest Legionella news, new legislation, best practice, R&D and much more…

Useful downloads…

  • HSE ACOP L8 – Control of Legionella
  • HSG274 Part 1 – Evaporative Cooling
  • HSG274 Part 2 – Hot & Cold
  • HSG274 Part 3 – Other Risks
  • Positive Legionella Tests – What To Do?
  • HSG282 – Spa Pools
  • Legionnaires’ – Duty Holders Guide
  • Health & Safety – Care Homes
  • Scalding Risks – Health & Social Care
            © Copyright 2026 - Legionella Control International Ltd.
  • Link to X
  • Link to Facebook
  • Link to LinkedIn
  • Home
  • About
  • Contact
  • FAQ
  • Disclaimer
  • Privacy
  • Modern Slavery
  • Reviews
  • Sitemap
Link to: Using Expert Witnesses in Legionella Cases Link to: Using Expert Witnesses in Legionella Cases Using Expert Witnesses in Legionella CasesUsing an expert witness in Legionella cases Link to: HSG282 Control of Legionella in Spa Pools Link to: HSG282 Control of Legionella in Spa Pools HSG 282 Control of Legionella in Spa Pools & Hot TubsHSG282 Control of Legionella in Spa Pools
Scroll to top Scroll to top Scroll to top

This site uses cookies. By continuing to browse the site, you are agreeing to our use of cookies.

OKLearn more

Cookie and Privacy Settings



How we use cookies

We may request cookies to be set on your device. We use cookies to let us know when you visit our websites, how you interact with us, to enrich your user experience, and to customize your relationship with our website.

Click on the different category headings to find out more. You can also change some of your preferences. Note that blocking some types of cookies may impact your experience on our websites and the services we are able to offer.

Essential Website Cookies

These cookies are strictly necessary to provide you with services available through our website and to use some of its features.

Because these cookies are strictly necessary to deliver the website, refusing them will have impact how our site functions. You always can block or delete cookies by changing your browser settings and force blocking all cookies on this website. But this will always prompt you to accept/refuse cookies when revisiting our site.

We fully respect if you want to refuse cookies but to avoid asking you again and again kindly allow us to store a cookie for that. You are free to opt out any time or opt in for other cookies to get a better experience. If you refuse cookies we will remove all set cookies in our domain.

We provide you with a list of stored cookies on your computer in our domain so you can check what we stored. Due to security reasons we are not able to show or modify cookies from other domains. You can check these in your browser security settings.

Google Analytics Cookies

These cookies collect information that is used either in aggregate form to help us understand how our website is being used or how effective our marketing campaigns are, or to help us customize our website and application for you in order to enhance your experience.

If you do not want that we track your visit to our site you can disable tracking in your browser here:

Other external services

We also use different external services like Google Webfonts, Google Maps, and external Video providers. Since these providers may collect personal data like your IP address we allow you to block them here. Please be aware that this might heavily reduce the functionality and appearance of our site. Changes will take effect once you reload the page.

Google Webfont Settings:

Google Map Settings:

Google reCaptcha Settings:

Vimeo and Youtube video embeds:

Other cookies

The following cookies are also needed - You can choose if you want to allow them:

    Download our Legionella Risk Assessment Checklist for business owners, landlords, property managers and health and safety specialists and start managing your legionella risk today.