A. Tsakalidis Inc.
12, Tsamadou street
GR-18531 Piraeus
T. +30 210 41 75 865
F. +30 210 41 72 895
info@tsakalidislabs.gr
www.tsakalidislabs.gr
G.E.MI. No: 54730809000
17/06/2022
5 most frequently asked questions & answers about Legionella
What is legionellosis and how is it transmitted?
Legionellosis is an infection caused by gram-negative bacteria of the Legionella genus. Twenty four of 58 known Legionella species have been implicated in human disease.
Transmission from contaminated environmental sources occurs via inhalation of aerosols or aspiration of fluid. Inhalation takes place when Legionella cells or particles containing them enter the respiratory tract, with aerosol sizes of <10 μm needed for alveolar deposition. Aspiration occurs most often in laying patients or those with throat obstructions.
As humans are an incidental host for Legionella, Legionellosis is not typically considered transmissible from person-to-person; however, a single case has shown such evidence.
Transmission from contaminated environmental sources occurs via inhalation of aerosols or aspiration of fluid. Inhalation takes place when Legionella cells or particles containing them enter the respiratory tract, with aerosol sizes of <10 μm needed for alveolar deposition. Aspiration occurs most often in laying patients or those with throat obstructions.
As humans are an incidental host for Legionella, Legionellosis is not typically considered transmissible from person-to-person; however, a single case has shown such evidence.
Are there any climatic trends associated with legionellosis?
Legionella can be found in various environments, while appearing naturally in fresh water and on land. Although a wide variety of sources have been associated with Legionellosis, heated water systems (optimum growth temperature between 28 and 40°C) are considered to be the main source for the appearance and transmission of Legionella.
Legionellosis follows a distinct seasonal pattern of occurrence, with maximum frequency during the summer. The warm weather has been shown to be associated with increased presence of Legionella in natural water systems.
However, research has shown that additional factors such as rain, high humidity and low pressure affect the transmission of Legionellosis.
Legionellosis follows a distinct seasonal pattern of occurrence, with maximum frequency during the summer. The warm weather has been shown to be associated with increased presence of Legionella in natural water systems.
However, research has shown that additional factors such as rain, high humidity and low pressure affect the transmission of Legionellosis.
Is it possible to transmit Legionella at home?
Based on epidemiological data, a person is more likely to be infected from Legionellosis in public places, such as hospitals, nursing homes, hotels, catering, accommodation and sports facilities, rather than in private spaces.
As most Legionella transmissions, are related to the aerosol of bacteria from water to air, the transmission is probably greater in areas that contain structures or equipment that facilitate aerosol production as showers, swimming pools, spas, and hot tubs, central air conditioning cooling towers, medical nebulizers and steam irons. Cases of Legionellosis have also been associated with decorative fountains and aquariums.
Although most of the reported cases of Legionellosis occur in large buildings environment, both its presence and transmission can occur in residential structures.
Large buildings appear more often as possible Legionellosis sourses because
As most Legionella transmissions, are related to the aerosol of bacteria from water to air, the transmission is probably greater in areas that contain structures or equipment that facilitate aerosol production as showers, swimming pools, spas, and hot tubs, central air conditioning cooling towers, medical nebulizers and steam irons. Cases of Legionellosis have also been associated with decorative fountains and aquariums.
Although most of the reported cases of Legionellosis occur in large buildings environment, both its presence and transmission can occur in residential structures.
- In these areas there are many people exposed to possible infection resulting in more cases and
- It is more likely if someone gets sick in these areas, to receive health care and the incident to be recorded.
What are the main sources of Legionellosis?
Legionellosis, sporadic or associated with outbreaks, is in most cases associated with plumbing, refrigeration or aerosol production systems, and medical equipment.
Important resources in the built environment include:
- Water storage tanks and plumbing (e.g. showers, taps and toilets)
- Cooling towers (it’s perhaps the most widely known source of Legionella. These devices can produce large volumes of aerosols from a heated water source that is frequently contaminated with Legionella and their aerosols can be produced over long periods of time and spread over long distances).
- Respirators (e.g. humidifiers, vaporizers, and nebulizers)
- Home air conditioning units (HVAC) which together with showers are considered the most likely source of Legionella aerosols in houses
- Water storage tanks in greenhouses or outdoors
- Swimming pools including spa, hot tub and Jacuzzi
- Steam generators and steam irons
- Decorative fountains and Aquariums
- Windshield wiper fluid storage systems in cars
- Sewage and biological treatment plants (many studies have shown that bio-aerosols released from wastewater treatment plants and sewage may contain very high concentrations of Legionella)
What practices can we adapt to reduce disease transmission?
The key to preventing Legionnaires' disease is to reduce the risk of developing and spreading Legionella.
Building owners and managers can do this by maintaining building plumbing systems and applying Legionella controls and testing.
There are many practices that contribute to the reduction of growth and transmission of Legionella in built-up areas. However, we must take under consideration the fact that, since Legionella is transported from water to air, practices should focus on the main sources of Legionella preventing growth and emitting of it in the air.
The major ones are:
Building owners and managers can do this by maintaining building plumbing systems and applying Legionella controls and testing.
There are many practices that contribute to the reduction of growth and transmission of Legionella in built-up areas. However, we must take under consideration the fact that, since Legionella is transported from water to air, practices should focus on the main sources of Legionella preventing growth and emitting of it in the air.
- Design and implementation of a water management program
- Implementation of chemical and microbiological testing of water in collaboration with an accreditated lab in frequency defined by current legislation in force
- Application of physical and chemical control methods on accessible hydraulic systems and frequent cleaning to prevent development of biofilm
- Maintaining the temperature of hot water circulating in the systems, above 60o C to reduce the bacteria growth
- Control of pH and disinfectant
- Keeping records of disinfectant / pH measurements and maintenance activities.
- Maintain filtration and recirculation systems according to the manufacturer's recommendations
- Repair the equipment or its components before they break down
- Imposition of bathers limits for swimming pools, spas, etc.
- Selection of home and car air conditioning units that do not use water to cool the air, therefore do not pose a risk to the development of Legionella
