Legionnaires Disease – What you need to know

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Legionnaires Disease

Legionnaires’ disease is a respiratory infection that primarily affects the lungs. Legionellosis is a group of illnesses caused by Legionella bacteria, including the most severe form of Legionnaires disease, as well as Pontiac fever and Lochgoilhead fever, which are similar but less serious diseases. Although everyone is susceptible to Legionnaires’ disease, a fatal form of severe pneumonia, some people are at higher risk than others.

People who are at higher risk of legionnaires disease include:

  • people over 45 years of age
  • smokers and heavy drinkers
  • people suffering from chronic respiratory or kidney disease
  • diabetes, lung (including chronic lung disease) and heart disease
  • anyone with an impaired immune system

Any person with one of the above is deemed to have an increased risk of contracting Legionnaires disease, however this risk is greatly increased where more than one is presented.

The incubation period from Legionella infection to developing Legionnaires disease

The incubation period, or time between exposure to the infectious agent (legionella infection) and the onset of symptoms, for Legionnaires disease is two to 10 days. In some instances, such as with immunocompromised patients, more extended incubation periods have been observed. Prodromal (the period between the appearance of initial symptoms and the full development of a fever.) symptoms, or early signs of illness, include headache, muscle pain (myalgia), weakness and fatigue (asthenia) and loss of appetite (anorexia).

The most common signs and symptoms are a high fever up to more than 40oC (104oF), which can be accompanied by a slow heart rate (relative bradycardia); cough, which is productive of purulent sputum in approximately 50% of patients; difficulty breathing (dyspnea); neurological abnormalities such as confusion, delirium and lethargy; muscle or joint pain (myalgia or arthralgia); diarrhoea; chest pain, which is often worse on inspiration (pleuritic) and on the side affected by pneumonia; headache; and, nausea or vomiting.

Legionnaires Disease 3

A few people who contract Legionnaires disease may also experience non-respiratory symptoms such as a ruptured or enlarged spleen, pericarditis (inflammation of the material around the heart), myocarditis (heart muscle inflammation), arthritis, renal failure, infections at incision sites and/or central nervous system infections.

Lab tests might show low blood sodium (hyponatremia), low blood phosphorus (hypophosphatemia), abnormal liver function, elevated creatine kinase, high C-reactive protein levels, and blood in the urine (microscopic hematuria). The findings below are typical for Legionnaires disease, but can also be indicative of other illnesses.

When reviewing a chest X-ray of a patient with Legionnaires disease, radiographic findings may include:

  • Pulmonary infiltrates (usually patchy and affecting only one lobe)
  • Consolidation of the surrounding lung tissue

Although there are no overt radiographic features associated with Legionnaires disease, all types of infiltrates have been reported in past cases.

Legionella bacteria and related bacteria are common in natural water sources such as rivers, lakes, and reservoirs, although they are generally present in low amounts. These systems may be found in buildings where they have a specific function, such as cooling towers, evaporative condensers, hot and cold water systems, and spa pools.

If the conditions are right, bacteria can multiply, increasing the chances of Legionnaires’ disease and prompting the need for appropriate precautions to be taken as outlined in Legionnaires disease – The Control of Legionella bacteria in water systems (L8).

Legionnaires Disease 2

Where does Legionella Bacteria come from?

Legionella bacteria are commonly found in freshwater sources, such as rivers and ponds. However, these circumstances are rarely suitable for acquiring the virus from these sources. Outbreaks of the illness typically happen when people are exposed to legionella that has been growing in man-made systems where water is kept at a temperature warm enough for it to thrive. These places include, but are not limited too, cooling towers, evaporative condensers, hot and cold water systems and spa pools found in all sorts of locations.s and homes.

How do people get Legionnaires disease?

People can develop Legionnaires disease by inhaling small water droplets suspended in the air that contain legionella bacteria. If certain conditions are present, the risk from the legionella bacterium is increased. These conditions include:

  • the water temperature in all or some parts of the system may be between 20-45 °C, which is suitable for growth
  • it is possible for breathable water droplets to be created and dispersed eg aerosol created by a cooling tower, or water outlets
  • water is stored and/or re-circulated
  • there are deposits that can support bacterial growth providing a source of nutrients for the organism eg rust, sludge, scale, organic matter and biofilms

What are the symptoms of Legionnaires disease?

The symptoms of Legionnaires’ disease are similar to the symptoms of the flu:

  • high temperature, feverishness and chills;
  • cough;
  • muscle pains;
  • headache; and leading on to
  • pneumonia, very occasionally
  • diarrhoea and signs of mental confusion

Legionnaires’ disease does not spread from person to person.

If you experience any of the aforementioned symptoms and fear that you might have Legionnaire’s Disease, consult your doctor immediately.

Because Legionnaires’ Disease shares similarities with the flu, it can be tricky to diagnose. Blood and urine tests can assist in detecting the disease. When doctors are already on alert for legionella bacteria in the area, they’ll have a head start on diagnosing patients correctly and earlier.

If you think your legionnaires’ disease is from your work, tell your manager and the health and safety representative. If your workplace has one, also tell the occupational health department. By law, employers must report cases of Legionnaires’ disease that may have happened at their business to the Health and Safety Executive.

How is Legionnaires disease treated?

Legionnaires’ disease is treated with antibiotics. The sooner therapy is started, the less likely the chance of developing serious complications.

Hospitalisation treatments for legionnaires disease may include:

  • antibiotics are given directly into a vein
  • oxygen through a face mask or tubes in your nose
  • a machine to help you breathe

When you start to get better you might be able to take antibiotic tablets at home. Antibiotic treatment usually lasts 1 to 3 weeks.

Most people make a full recovery, but it might take a few weeks to feel back to normal.

The extent of Legionnaires disease

Legionnaires disease is thought to be common around the world. The prevalence of Legionnaires disease varies largely depending on the surveillance levels reported. The prevalence is unknown as many countries have inadequate monitoring and diagnostic tools to detect and diagnose the infection or inadequate treatment methods. However, some studies have estimated that legionnaires disease may affect up to 10 million people worldwide.

There are a number of risk factors that can increase a person’s likelihood of being infected with legionnaires disease, including age, certain medical conditions, and environmental conditions. People who are over the age of 65 or have other underlying health conditions such as lung disease or diabetes are at a higher risk of developing legionnaires disease. Additionally, exposure to warm and humid environments, as well as exposure to contaminated water sources, can increase the risk of infection.

Complications of Legionnaires’ disease

Legionnaires disease may cause serious health issues and deteriorating organs and muscles. These are:

  • Pneumonia: This is a common complication of legionnaires disease and can cause inflammation in the lungs, which leads to difficulty breathing and shortness of breath.
  • Brain infection: In some cases, legionnaires disease can lead to inflammation of the brain and nervous system, which may cause confusion, delirium, and seizures.
  • Organ failure: In severe cases, legionnaires disease can lead to kidney or liver failure, which may require surgical intervention or life-support measures.

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