Legionellosis: What is Legionnaires Disease?


Legionnaires’ disease is a type of pneumonia that is due to a bacterium known as Legionella, which was first discovered in 1976. The disease was first reported after an outbreak at an American Legion convention. Patients who present with symptoms of pneumonia are often tested to determine if the illness is in fact Legionnaires’.

Every year in the United States the CDC reports anywhere from 8,000 to 18,000 cases of people being hospitalized with Legionnaires’ disease. That being said, there are also a high number of cases that are not properly diagnosed or reported, so these figures are actually much higher.

This disease is considered to be a notifiable disease in which health districts can pinpoint outbreaks by means of the National Notifiable Diseases Surveillance System (NNDSS).

Legionnaires’ disease can be deadly. A study of cases that have been reported to the CDC found that there is roughly a forty percent death rate for cases that are acquired in the hospital, and a twenty percent death rate for cases that are acquired somewhere in the community. There have been outbreaks that have as high as a fifty percent death rate.

As previously mentioned, Legionnaires’ disease is a serious type of pneumonia. Symptoms of the disease usually start within two to fourteen days after being exposed to the Legionella bacteria. Symptoms can include: headaches, nausea, fever, vomiting, fatigue, chills, diarrhea, chest pain, confusion, shortness of breath, loss of appetite, muscle aches, and a cough that may produce blood or mucus.

When it is suspected that a patient has pneumonia, tests are often conducted to determine whether or not it was caused by the Legionella bacteria. This bacterium cannot be spread from one person to another. It is spread mostly by water, but can also grow in any damp, warm setting. People can contract Legionnaires’ disease in the following ways:


This happens when water or other types of liquids that have been contaminated with the bacteria enters the lungs. Cases that are acquired in the hospital are sometimes related to aspiration because of using equipment that has been contaminated.


A number of cases of Legionnaires’ disease are due to breathing in mist that contains Legionella. This has been linked to swimming pools, whirlpools, showers, fountains, faucets, and cooling units found in air conditioning.


There have been a few cases of people becoming ill with Legionnaires’ disease after working with contaminated soil while gardening or by stirring up earth on construction sites.
Outbreaks of this disease are classified when two or more people fall ill after being in the same place at roughly the same time. Outbreaks have been linked to hospitals, hotels, nursing homes, and cruise lines.
Complications can arise after contracting the disease. Legionnaires’ affects mainly the lungs, but can also impact other organs such as the kidneys and heart. Other complications can include:

Respiratory Failure:

This is the main cause of death in patients who contract Legionnaires’. This typically happens when they are changes in the mechanical makeup of the lungs, or the arteries have experienced a loss of oxygen.


This is an infection of the inner lining, also known as the endocardium, of the heart. This happens when the Legionella bacteria spread throughout the bloodstream. When the infection takes place, the heart valves can become damaged.


This is an irritation and swelling of the membrane that surrounds the heart, known as the pericardium.
Acute Kidney Failure: This is when your kidneys suddenly lose the ability to rid the blood of excess waste and fluid. When this occurs, the body stores waste and fluid, which can be deadly.
Septic Shock: Legionella bacteria can cause blood pressure to drop suddenly, which can reduce the flow of blood to important organs such as the kidneys and the heart. This can be fatal as it can lead to multiple organ failure.

If an outbreak is suspected when two or more people are diagnosed with Legionnaires’ disease after staying at the same hotel, or the same cruise ship, testing is done to verify the source of the outbreak.
In order to determine the source of the bacteria, a visual inspection is conducted. Health officials will visually examine key areas of the hotel, cruise ships, office building, etc. These areas typically include air conditioning systems, hot water tanks, storage tanks, swimming pools, whirlpools, spas, ornamental fountains, and all potable water systems.

If it is found that the hotel or other inhabitable area needs to be tested for Legionella bacteria, samples are typically obtained from air conditioning systems, spa and pool filters, water tanks, hot water heaters, showers, sings, and anywhere else people may have come into contact with the disease.

The test to determine if Legionnaires’ disease is present looks for the bacteria itself, and the precise species of the bacteria. More testing can be done to determine the species more precise serotype. For example, the species Legionella pneumophila has fifteen different serogroups. Even more in depth testing can be done to find the serogroup’s specific molecular subtype. If the culture method is what people that fell ill were diagnosed with, testing can be done to find out if the Legionella that caused their illness has the same molecular subtype as the bacteria located in the hotel or other area in question. The results of these tests can be used as valuable evidence in the event that a lawsuit is filed against the establishment.

Cases of Legionnaires’ disease can also be linked to one another and a particular area by completing an epidemiological investigation. This is especially true if all of the people that have become ill stayed in the same location, at approximately the same time, and all came down with the same symptoms within a fourteen day period. Epidemiological findings can be used as evidence for a lawsuit as well.

If you or someone you know has become ill with Legionnaires’ disease, you should contact a personal injury attorney promptly. He or she can review your case, and help you pursue a claim against the parties responsible for your illness.

Article by Christopher Price