What is Legionella?

Legionella is a type of pathogenic bacterium. Legionella is somewhat common; there are about 50 different species of Legionella. Despite being common, the Legionella bacteria can make people very sick. Legionella Pneumophilia, just one type of legionella, causes legionellosis, otherwise known as Legionnaires’ Disease and the different variations of this illness.

Is it new?

While legionella is not new, it is a newer discovery for us. In July of 1976, 221 people became ill and 34 died from a then unknown disease. This illness broke out in individuals who attended an American Legion convention in Philadelphia held during the United States’ Bicentennial, hence the name Legionnaires’ Disease. Several months later, the bacterium was identified as the cause of the epidemic and it was named after the disease it can cause.

Where is it found?

Legionella is known to live inside amoebae in water. It is usually found naturally in freshwater streams, rivers, lakes, and ponds. Legionella has now also commonly come to be found in cooling towers, swimming pools, fountains, home hot-water supplies, and other warm water locations. Some types of legionella live in other environments as well; one species has been found to be common in potting soil.

How does legionella make people sick?

Legionella is taken in when droplets or mist containing the bacteria are inhaled, which usually means that the bacteria is airborne. If legionella becomes airborne, some reports state that it can travel about four miles from its source. Legionella can also be aspirated into the lungs; if contaminated water is aspirated, or choked on, the droplets will take the bacterium directly into the lungs.

Up to 20% of all infections caused by legionella can be traced to home hot water supplies and heating systems. Legionella and other bacteria can grow in the biological slime that can settle and grow on the inside of these pipes.

Will it make me sick?

While legionella naturally occurs in several environments it does not necessarily make people ill. Those who are otherwise healthy may not show any symptoms, but the elderly and those with respiratory problems, compromised immune systems, and smokers are more likely to become sick. How to kill legionella?

As Legionella can be fatal, it is important to know what to do to stop the growth and spread of this bacterium. While scientists seem to disagree on the exact temperature, it seems that this bacterium thrives and multiplies in the temperature range of approximately 70°F to 113°F, and boiling water can kill Legionella. This means that while home hot water supplies, a common source of legionella, are commonly kept on the warm side to prevent scalding, it is best to turn up the heat to kill off legionella.

There are also chemical solutions to kill legionella. Chlorine and chlorine dioxide in proper concentrations can kill off this bacterium. The processes of copper-silver ionization and moist heat sterilization are also capable of eliminating legionella.