Legionella in the environment

The genus Legionella belongs to a large number of species, and the main representative is Legionella pneumophila, which is responsible for 85% of all diseases caused by legionella.

The bacterium Legionella pneumophila was first discovered in 1976 after an epidemic of pneumonia broke out among American legionnaires. The disease occurs when bacteria with tiny droplets, ie. aerosols reach the pulmonary alveoli.

It is widespread in nature. Although the disease caused by legionella occurs throughout the year, it is much more common in summer due to greater exposure of people to bacterial sources such as humid air, air conditioners, swimming pools, saunas. The natural habitats of legionella are rivers, lakes, streams, cooling towers, hot springs, fountains, then process and cooling water within industrial plants.

It can also colonize the water distribution network, which is an important way of spreading legionella, which can thus reach hospitals, recreation centers, households.

The bacterium is very resistant and can survive in a wide range of environmental conditions, from 0ºC to 63ºC and pH values ​​from 5.0 to 8.5. It survives for years in water at a temperature of 2ºC to 8ºC, but in the dormant phase. It is tolerant to chlorine and resistant to the process of water chlorination, and the primary factor for growth and reproduction is L-cysteine, in the presence of iron.

The primary task during prevention is the control and disinfection of the reservoir of infection, and especially the water distribution network, with the aim of protecting the entire population. As the bacterium is resistant to chlorine, other methods are used for its inactivation and removal, such as filtration, heating to a temperature of up to 70ºC, copper – silver ionization and similar procedures. Monitoring of legionella is important in order to identify environmental sources that may pose a risk of developing the disease, ie. legionellosis.

SP Laboratory proves the presence of Legionella by the accredited method in accordance with SRPS EN ISO 11731: 2017 – Water quality – Determination of Legionella number

In the domestic Regulations, testing for the presence of Legionella pneumophila is defined in the Safety regulations of pool water, Annex 1 – Parameters of health safety of pool water (“Official Gazette of RS”, No. 30/2017 and 97/2017).