Legionnaires’ disease, or legionellosis, has as its causative agent the bacterium LEGIONELLA PNEUMOPHILA, which is the most common but also dangerous species of the LEGIONELLA family.

General information

The Legionella bacterium grows in surface waters, but can also be detected in clean water and survives even in distilled water. Ideal propagation conditions of LEGIONELLA are water distribution networks of the buildings and especially in the hot water distribution network (temperature higher than 20o C). The number of colonies increases, forming a biofilm. The biomembrane is a permanent source of possible contamination of the water of distribution networks of the buildings, constantly releasing microorganisms in the drinking water. The problem of biomembrane formation becomes more acute mainly in large buildings with a complex and extensive piping system.

The transmission of the bacterium is mainly aerogenic through the fine droplets in the form of an aerosol.

Legionella on  E/M installations

In all E/M installations where we find a concentration of water temperatures between 20°C  – 42°C with an ideal temperature of 35°C,we must take into account the possibility of developing the bacterium.

• Industrial installations
• Hotel facilities
• Building facilities with central networks, air conditioning-heating HVAC
• Swimming pools, spa

Several possible points are encountered such as:

• Tanks of hot and cold water.
• Pipes with little or no water flow e.g. unoccupied rooms in hotel units.
• Sediments(biomembranes)and impurities of the inner surfaces of pipes and tanks.
• Rubberfibres and natural fibres in  anti-friction  rings and waterproofing  devices
• Water heaters and hot water tanks.
• In salt deposits and corrosions in pipes, showers and faucets.
• Swimming tanks (especially those where the water is hot)
• Fountains
• Atmosphere humidifiers and breathing apparatus operated by tap water

Prevention

The better approach to the phenomenon, is the determination of preventive actions, case management actions and possible interventions of existing equipment.

Thus, the initial approach begins with the Occupational Risk Assessment Study, where the critical points of the installation are identified and the corresponding actions are proposed.

Of course, the Risk assessment must take into account any new data that arise and make the appropriate adjustments.

Specifically, some actions are:

• Disinfection of all possible sources of exposure to legionella with chlorine, cleaning of heating tanks and tanks, as well as an increase in the temperature of circulating hot water, if this is below 50°C:
• Interventions with additional filters
• Avoiding points of existence of stagnant water
• Adding appropriate chemical disinfectants depending on the use of the equipment (cooling towers, swimming pools, etc.), especially if operating temperatures favor the growth of bacteria
• Replacement of water by drainage and refilling in accordance with the relevant legal instructions
• Frequent water sampling and cooperation with a specialized laboratory for chemical analysis
• Take special care when restarting equipment that has not been in use for some time

The above article is for informational purposes only and does not constitute a prevention study against the Legionella bacterium.

Bibliography

1. LEGIONELLA and the prevention of legionellosis Jamie Bartram, Yves Chartier, John V Lee, Kathy Pond and Susanne Surman-Lee
2. MINISTRY OF HEALTH, CIRCULAR “Prevention of the disease of legionnaires”, Athens, 29 -07-2019,, Δ1 (δ) / ΓΠ οικ. 56075
3. European technical guidelines for the prevention, Control and Investigation of Infections caused by Legionella species, June 2017
4. PREVENTIVE MEASURES IN HYDRAULIC & AIR CONDITIONING INSTALLATIONS FOR THE AVOIDANCE OF CREATION OF INFECTION HOURS-
5. LEGIONARY DISEASE, www.legionela.gr
6. Legionellosis – Legionnaires’ Disease, https://eody.gov.gr/disease/legionellosi/
7. Health and Safety Executive (HSE), Managing legionella in hot and cold water systems