Legionella genus bacteria are found in natural aquatic environments and also in artificial systems, such as water supply/distribution networks, building networks for hot and cold water, air conditioning and cooling systems (cooling towers, evaporative condensers and humidifiers) in buildings, namely in hotels, spas, shopping centers and hospitals.
They also appear in ornamental fountains and recreational tanks, such as jacuzzis. Currently, more than 50 species of Legionella are known, of which Legionella pneumophila is the most frequent in the identified clinical cases, but it is not the only one that can infect humans. There are approximately 70 distinct serogroups, many of which are considered pathogenic.
Exposure to this bacterium can cause a respiratory infection, currently known as Legionnaires’ Disease, so called because, after the American Legion Convention, in 1976, at the Bellevue Stratford hotel, in Philadelphia, 34 participants died and 221 fell ill with pneumonia.
The infection is transmitted by inhalation of droplets of contaminated water vapor, aerosols, of such small dimensions that they transmit the bacteria to the lungs, allowing its deposition in the pulmonary alveoli. Ingestion of the bacterium does not cause infection, nor is it contagious from person to person.
The disease affects especially adults, between 40 and 70 years of age, with a higher incidence in men. Smokers, people with chronic respiratory problems, kidney patients and, in general, immunosuppressed, are more likely to contract this disease. Symptoms include high fever, chills, headaches and muscle aches. In a short time, a dry cough and, at times, breathing difficulties appear, in which in some cases diarrhea and/or vomiting may develop. The patient may also be confused or even go into delirious episodes.
The disease has occurred in the form of sporadic cases or epidemic outbreaks, particularly in the summer and autumn, with greater expression in tourist areas. In Portugal, the disease was detected for the first time in 1979 and belongs to the list of Diseases of Compulsory Declaration (DDO). From 2000 to the end of 2010, 685 cases were reported, predominantly associated with accommodation in hotel units, although more recently there have also been outbreaks in factories and hospitals. Fatality rates have been estimated at 5 – 30% of the total cases.
Due to its natural characteristics, Legionella is a microorganism that is not easily controlled by conventional water treatments and, therefore, the potability of water is no guarantee of its absence in water, regardless of its source. In addition to these difficulties, common factors in Legionellosis outbreaks in the USA have been:
- Lack of familiarity with how water is processed in water systems in complex buildings;
- Lack of effective microbiological control;
- Lack of coordinated prevention efforts.
Legionella is a risk arising from human activity, since in its natural habitat it does not represent a predictable risk and, therefore, whoever designs, manages, operates or owns a building is ultimately responsible for damage that their water systems and components (showers, cooling towers, decorative fountains, spas, jacuzzis, indoor pools, humidifiers, irrigation systems, among others) will cause the life and health of others.
Since this problem is fundamentally the result of the processing of drinking water in buildings, the solution for the prevention of Legionella is the implementation of a continuously active risk management plan, as well as the monitoring and minimization of these risks.
AQUALAB carries out the Legionella Risk Assessment, assisting its customers in the task of identifying, managing and minimizing the risks of this bacterium for the protection of its employees, customers, guests, visitors and the community around them. We carry out an evaluation of all components and activities of operation of the water systems of buildings (hospitals, shopping centers, hotels, businesses, etc.) to identify hazards, classify risks and, finally, suggest an improvement plan in order to manage the Legionella risk in each system.
In our risk assessment, the HACCP method (risk control method widely used in the food industries) is used, which is considered the most suitable for this type of assessment and which is based on the most important and recognized technical standards accepted worldwide for Legionella risk management, such as the World Health Organization (WHO/UN), OSHA in the USA (Occupational Safety and Health Administration), HSE in the United Kingdom (Health and Safety Executive).