Basic Legionella Facts You Should Know

First recognized in 1976, Legionnaires’ disease is a severe form of pneumonia caused by the bacterium Legionella pneumophila and other Legionella species. Legionella naturally live in in water and are most commonly found in water systems containing warm water such as hot tubs, cooling towers, and hot water tanks. This bacterium is considered a biohazard by the CDC and an estimated 10,000 - 18,000 become infected each year in the US.

Legionnaires’ disease can be hard to diagnose, as its symptoms are nearly identical to other pneumonias including a high fever, chills, muscle aches, headaches, etc. The diagnosis is often missed because Legionella do not grow well on standard microbiology agar media – a urine antigen test is the primary diagnostic tool for Legionella pneumophila serogroup 1 – but it is not able to detect other serogroups or Legionella species associated with human disease. Below are 6 basic, yet essential facts about legionella that we feel you should know.

1. There are two different illnesses that legionella bacteria cause: Legionnaires’ disease, the lethal pneumonia and Pontiac fever, a milder influenza-like illness.

2. Legionella bacteria in water systems are be difficult to detect, especially with culture methods. These water systems can produce  Legionella-containing aerosols that are inhaled and cause  a serious pneumonia.

3. Though hospitalization is required to treat Legionnaires’ Disease, also called legionellosis, it is treatable with antibiotics if the pneumonia is promptly diagnosed.

4. There are some complications caused by legionellosis, mainly respiratory failure, septic shock and acute kidney failure. Early antibiotic treatment is the best line of defense to prevent these complications.

5. Legionnaires’ disease does not spread from person to person (only one exception to this is in the published literature), it is contracted by breathing in contaminated aerosol or small droplet vapor.

6. The most effective way to prevent legionella from multiplying in water systems is proper maintenance, whether it’s your home’s hot water tank or corporate cooling tower. Legionella water testing is performed to determine whether your maintenance program is working.