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Legionella

In HVAC systems, the management of the legionella pneumophila risk is ensured through application of our Alisea Guaranteed Method. However, because Legionella Bacteria often grows within water systems, Alisea recommends an advanced protocol for Analysis and Risk Assessment.

The enclosed places where we live and work, such as homes, offices, restaurants, gyms, hospitals, are continuously subjected to sources of chemical and microbiological pollution.

In addition to HVAC systems, water systems can be fertile ground for the proliferation of micro-organisms harmful to our health, mainly due to the presence of stagnant water that turns into a veritable basin prone to infectious outbreaks.

Alisea has developed an advanced Risk Analysis and Evaluation protocol to address the risk of Legionella bacteria within the water systems.

Legionellosis, or "Legionnaire's disease", is a serious, often fatal, infectious disease.

Legionellosis is a gram-negative aerobic bacteria of the genus Legionella, which can occur either in the form of pneumonia, in extra pulmonary febrile form or in subclinical form.

The bacteria of the Legionella genus are naturally found in aquatic environments such as waterways, lakes, thermal waters, etc. From its natural state, however, the micro-organisms can pass through artificial reservoirs (water and air-conditioning systems, swimming pools, fountains, irrigation systems, etc.).

The mode of transmission to humans is normally respiratory, through inhalation of aerosol containing legionellae, or dry particles in the air. Currently, the main aerosol generating systems that have been associated with the transmission of the disease include air conditioning systems, water systems, equipment for assisted respiratory therapy, hydro massages, pools and decorative fountains. In scientific literature, cases of legionellosis acquired by aspiration or microaspiration of contaminated water and cases of transmission through open wounds have been reported. Additionally, human transmission has never been scientifically demonstrated.

Epidemic outbreaks have repeatedly occurred in man-made environments of temporary residence, such as hospitals and hotels.

The adoption of preventive measures are justified by the high lethality rate of legionellosis: 5-15% of infections of EU origin and 30-50% of those of nosocomial origin. For patients in precarious clinical conditions and in those treated late, the lethality index can be as high as 70-80%.

"Pontiac Fever", after an incubation period of 24-48 hours, manifests itself in an acute form without pulmonary sypmtoms, like a flu, and resolves in 2-5 days. The symptoms are: general discomfort, myalgia and headache, followed quickly by fever, sometimes with cough and reddened throat. Other symptoms include diarrhea, nausea and mild neurological symptoms such as dizziness or photophobia.

"Legionnaire's disease", after an incubation period varying from 2 to 10 days (on average 5-6 days), manifests itself with clinically significant or considerable gravity lobar lung involvement, with or without extra pulmonary implications. The pulmonary symptoms are onset quickly, with malaise, headache, fever and osteoarthritis, a mild, non-productive cough, which is accentuated with the appearance of respiratory symptoms. At the objective examination of the thorax, areas of single or bilateral parenchymal thickening are noticed, with hypophones and the presence of crackling rales. The radiological finding is not pathognomonic. Sometimes gastrointestinal, neurological and cardiac symptoms may be present; alterations in mental status are common but the signs of meningism are not. The patient suffering from legionellosis will show mental confusion, and generally has one or more of the following symptoms: relative bradycardia, slight increase in transaminases, hypophosphataemia, diarrhea and abdominal pain. Complications of legionellosis may include: lung abscess, empyema, respiratory failure, shock, disseminated intravascular coagulation, thrombocytopenic purpura and renal failure.

The first phase is represented by a  Risk Analysis during which all the "risk factors" arising from the presence of Legionella spp  in sanitary waters is determined. In this phase we analyze all the risks deriving from plant engineering factors (eg installed equipment, dormant piping, etc.), functional factors (eg operating temperatures, plant management, etc.) and human factors (eg type and conditions of occupant health, sensitive areas, etc.). Obviously this phase cannot ignore a microbiological monitoring of water in order to evaluate the concentrations of Legionella spp.

From the risk analysis and the microbiological monitoring results, a Risk Assessment Document is created which contains all the data, analysis and considerations gathered in the previous phase.

Based on the results collected, it may be necessary to implement Corrective Actions, also called “control measures” which, depending on the level of risk, may be different. The actions can be of a plant engineering-management nature (eg adjustment of operating temperatures, removal of dormant piping, etc.) or they can be restoration activities through reclamation of the water network.

These control measures are not carried out directly by Alisea personnel, but by specialized technicians and maintenance personnel, partners of our company for many years.

In order to assess the effectiveness of the treatment, post-intervention and microbiological checks are carried out in addition to a technical intervention report to Validate the work. In the event that the results are not positive, it is necessary to repeat the intervention until the abatement is complete and verified.

All interventions and analysis performed must be reported in a Risk Management Program.

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