Can You Die From Legionnaires Disease?

Can You Die From Legionnaires Disease?

With a diagnosis and treatment on time, legionnaires disease follows a positive course. Only in case of incorrect treatment, the disease can end in death in 20 to 50% of cases, especially in elderly people with weakened immune systems. Once a legionnaires disease has been overcome, the patients are not immune to the bacteria, but may become ill again.

Legionellosis is a serious infectious disease of the lungs, caused by the Legionella pneumophila. The name of the legionnaires disease comes from a meeting of veterans of the American air forces in a hotel in Philadelphia (USA) in 1976. In this hotel, 221 men became ill with a serious infection accompanied by symptoms such as cough, breathing difficulties and high fever. The doctors diagnosed pneumonia and treated the patients with penicillin. But the treatment proved ineffective and 34 men died. It was not until half a year later, when the pathogenic agent of the hitherto unknown disease could be identified.

Can You Die From Legionnaires Disease?

Legionella bacteria present in water do not directly threaten health. The infection occurs when the pathogen reaches the lungs through the nose, mouth or throat, either by water spray, for example when showering, or by air conditioners or hot tubs when inhaling the liquid. Humidifiers in work and residential areas and inhalers used in medicine can also be infectious foci. On the contrary, no direct transmission among humans is known.

Legionella bacteria are mixed in the lungs with monocytes, a type of leukocytes (white blood cells). The incubation period, that is, the time between the infection and the appearance of the disease is two to ten days.

Risk Factors

A large part of legionellosis patients have a weakened immune system. Either, for example, by the intake of medications that the patient must take for an organ and spinal cord transplant or for being undergoing chemotherapy to overcome leukemia. Other risk factors for legionnaires disease are long-term treatment with corticosteroids, a weakened body after a long surgical intervention, advanced age, smoking or excessive alcohol consumption.


Legionnaires disease first triggers symptoms are malaise, joint pain, headache and irritable cough. In about 90% of patients, it is Pontiac fever. With symptoms similar to the flu it does not usually evolve into pneumonia. In the remaining 10% of cases, pneumonia can occur due to Legionella, the real legionnaire disease. The symptoms are chest pain, chills, and high fever. Occasionally, stomachache with diarrhea and vomiting also appears. If the central nervous system is also affected by legionellosis, daze can occur which, in severe cases; can lead to a confusional state.

In legionnaires disease, the diagnosis is obtained from existing symptoms and additional information. Suspicion arises especially in case of pneumonia after a trip with a hotel stay. But definitive safety cannot be maintained until there is direct evidence of the pathogenic germ. To do this, certain proteins are looked for in the analysis of urine that only appears in case of infection by Legionella (specific antigens). A sample of the pharynx and lung can also be obtained. The exact type of germ can be identified microscopically after a culture.

If left untreated, legionnaires disease usually gets worse in the first week. As with other risk factors that cause severe pneumonia, the most common complications of legionnaires disease are respiratory failure, shock, and acute kidney and multi-organ failure. Healing, which always requires antibiotic treatment, is usually complete, although it may take several weeks or months. Rarely, severe progressive pneumonia or ineffective treatment can lead to brain sequelae.

The mortality rate due to legionnaires disease depends on the severity of the disease, the suitability of the initial antimicrobial treatment, the environment in which the infection was contracted and various factors related to the host (for example, the disease is usually more serious in immunosuppressed patients). In untreated immunosuppressed patients, the mortality rate can reach between 40% and 80%, although it can be reduced to 5% to 30% by appropriate case management and depending on the severity of the clinical signs and symptoms. In general terms, the mortality rate ranges between 5% and 10%.

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:July 22, 2023

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