What Is Legionnaires’ Disease? Essential Information

Legionnaires’ disease is a form of pneumonia caused by breathing in large amounts of Legionella bacteria. This bacteria is typically found in water sources such as hot tubs, cooling towers, and water systems in buildings. For high-risk groups, Legionnaires’ disease can even result in death.

This guide explores Legionnaires’ disease epidemiology, explaining the symptoms of the illness, transmission, treatment, and why Legionella risk assessments are so important. Stay informed and learn how to protect yourself and others from this harmful disease.

Why Is it Called Legionnaires’s Disease?

Legionnaires’ disease is named after an outbreak that occurred during a convention of the American Legion in Philadelphia in 1976. The outbreak affected a significant number of attendees, leading to severe respiratory illness and several deaths.

Investigations traced the cause to the presence of Legionella bacteria in the air conditioning system of the convention hotel. Since then, the illness has been commonly referred to as Legionnaires’ disease.

What’s the Difference Between Legionella and Legionnaires’ Disease?

Legionella refers to a type of bacteria belonging to the Legionellaceae family. Legionella bacteria are found in natural water environments and purpose-built hot and cold water systems alike.

Legionnaires’ disease, on the other hand, is the illness caused by inhaling aerosolised droplets containing Legionella bacteria. It is a severe form of pneumonia that can cause respiratory symptoms, explored in more detail below.

What Are Symptoms of Legionnaires’ Disease?

Legionnaires’ disease is characterised by symptoms such as high fever, cough, shortness of breath, muscle aches, headaches, and pneumonia. Additional symptoms may include chest pain, confusion, and gastrointestinal issues.

It is important to seek medical attention if these symptoms occur, especially after potential exposure to Legionella bacteria.

The Stages of Legionnaires’ Disease

Legionnaires’ disease typically progresses through the following stages that can vary in severity:

1. Incubation Stage: This is the initial period after exposure to Legionella bacteria, usually lasting between 2 to 10 days. During this stage, individuals may not experience any symptoms.
2. Early Symptoms: In the early stages, symptoms similar to flu-like illness may appear, including high fever, muscle aches, headaches, and chills. Other symptoms may include cough, shortness of breath, chest pain, and fatigue.
3. Pneumonia Stage: As the disease progresses, the infection can cause pneumonia, which is the inflammation of lung tissue. Severe cases may lead to respiratory failure, requiring hospitalisation and intensive care.

Who Is Most at Risk From Legionnaires’ Disease?

Certain individuals are more susceptible to contracting Legionnaires’ disease. These include older adults, particularly those over 50 years of age, as well as individuals with weakened immune systems, such as those with chronic illnesses or undergoing immunosuppressive treatments. Smokers, individuals with underlying respiratory conditions, and people with a history of heavy alcohol use may also be at greater risk.

It is important to note that anyone can potentially contract the disease if exposed to Legionella bacteria, but those with specific risk factors are more vulnerable to developing severe symptoms.

How Is Legionnaires’ Disease Treated?

Thankfully, Legionnaires’ disease is treatable. It is typically treated with antibiotics, specifically those that are effective against Legionella bacteria. The choice of antibiotic may depend on the severity of the infection and the individual’s overall health. It is important to promptly seek medical attention if you suspect Legionnaires’ disease, as early treatment can lead to better outcomes.

The specific treatment plan for Legionnaires’ disease should be determined by a healthcare professional based on the individual’s condition. In severe cases, hospitalisation may be required for intravenous antibiotic therapy and supportive care.

Is Legionnaires’ Disease Contagious?

Legionnaires’ disease is not typically spread from person to person. It is primarily contracted by inhaling small droplets of water contaminated with Legionella bacteria. However, it is important to note that the source of the contaminated water can potentially affect multiple individuals, especially in shared environments such as hotels, hospitals, or workplaces.

How Does Legionnaires’ Disease Spread?

Legionnaires’ disease spreads through the inhalation of aerosolised water droplets containing Legionella bacteria. Common sources of contamination include cooling towers, swimming pools, hot tubs, showers, fountains, air conditioning units, and other water systems that create and disperse these droplets. 

Proper maintenance, regular cleaning, and disinfection of water systems are essential for preventing the spread of Legionella bacteria and reducing the risk of Legionnaires’ disease.

What Is the Best Way to Prevent Legionnaires’ Disease?

To effectively manage the risk of Legionella exposure, regular Legionella risk assessments are essential. These assessments involve evaluating and controlling the potential sources of Legionella bacteria in water systems, ensuring the safety and well-being of individuals who may come into contact with the water.

In accordance with UK legislation, employers, landlords, and individuals responsible for premises have a legal obligation to evaluate and manage the risk of Legionella bacteria exposure within their water systems. This requirement is established under the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health (COSHH) Regulations 2002. 

Compliance with these regulations ensures the protection of individuals and the promotion of a safe working and living environment.