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What Is The Mortality Rate Of Legionnaires’ Disease?

Legionnaires’ disease is a serious condition characterized by the inflammation of the lung caused by bacteria named Legionella. It is a severe type of pneumonia that can cause death. It is transmitted through drinking water, inhaled water droplets containing the bacteria and contaminated soil. The symptoms of the disease are similar to flu i.e. high fever, headache, muscular pain, nausea, vomiting, and diarrhea. Untreated Legionnaires’ disease may get worse in the first week itself and can cause death due to progressive pneumonia, respiratory failure, shock or multi-organ failure.

What Is The Mortality Rate Of Legionnaires’ Disease?

Legionnaires’ disease is a serious ailment of lungs caused by Legionella bacteria. Exposure to legionella bacteria does not mean that every individual can catch the infection. There are certain factors that can risk you to contract the disease.

The risk factors that can lead to the infection of lungs by legionella bacteria are-

Weakened Immune System- people who have a weakened immune system due to chronic diseases like diabetes, other lung infections, cancer or who are immune compromised in diseases like HIV or AIDS can contract the infection easily. Those who are consuming certain medications such as corticosteroids or drugs that can prevent rejection of an organ after transplantation can also catch the infection.

Smoking –regular smoking can reduce the strength of the lungs to fight infection as it damages the lung. Those who smoke are at more risk to catch the infection by Legionella.

Old Age- people above the age of 50 years are more susceptible to catch the infection.

Legionnaires’ disease is most commonly spread by inhalation of contaminated water droplets present in air formed due to water sprays, jets or mists or by aspiration of contaminated water or ice. It can represent itself with mild febrile conditions to severe pneumonia leading to respiratory failure.

The symptoms of Legionnaires’ disease are-

  • Chilliness
  • High-grade fever with temperature 104 F
  • Muscle pain
  • Headache
  • Cough mixed with blood and mucus
  • Pain in the chest
  • Shortness of breath
  • Stomach disorders like nausea, vomiting or diarrhea
  • Confusion or alteration in mental states

Legionnaires’ disease can cause life-threatening complications such as-

Respiratory Failure- weak lungs or lungs affected by chronic diseases are more susceptible to catch the infection by Legionella, which may complicate into respiratory failure. It is a condition where the lungs are unable to exchange oxygen and carbon dioxide in the body.

Septic Shock- when the blood pressure drops suddenly due to an infection, the blood supply to vital organs of our body especially to the brain and kidneys get hindered, leading to a condition called septic shock. In this condition, the blood supply is compensated by the heart as it pumps increased volume of blood to meet the shortage. This result in the weakening of the heart and blood flow reduces more.

Acute Renal Failure- Legionnaires’ disease may lead to sudden loss of the normal functioning of the kidneys. This may cause accumulation of waste products and fluids to the dangerous levels in the body.

Thus, when Legionnaires’ disease is not treated efficiently or left untreated, it may cause serious complications as discussed above which may lead to death. It is more dangerous in people with weakened immunity. According to WHO, the mortality rate due to Legionnaires’ disease in immune suppressed people is 40-80% who have been not treated and it is 5 to 30% for those who have received the treatment. 1 out of every 10 patients of Legionnaires’ disease dies due to its complications.


Legionnaires’ disease is a bacterial infection of lungs that can be fatal. It is a life-threatening form of pneumonia which needs immediate medical attention as it may complicate into dangerous conditions like respiratory or kidney failure and septic shock which may lead to death.


  1. Centers for Disease Control and Prevention (CDC) – Legionnaires’ Disease: https://www.cdc.gov/legionella/about/index.html
  2. Mayo Clinic – Legionnaires’ Disease: https://www.mayoclinic.org/diseases-conditions/legionnaires-disease/symptoms-causes/syc-20351747

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 4, 2023

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