The Legionelosis is a generic term that is used to refer to the illness that causes the bacterium Legionnaire's disease pneumophilla and others of the same genre. It appears fundamentally in two clinical forms perfectly differentiated:

• a pneumonia that knows horn Legionnaires' disease,
• a type picture gripal and light character that is named a Fever of Pontiac.

The first description of an epidemic pneumonia by Legionnaire's disease pneumophila was described in 1977 in a convention of the American Legion, which is an association type ONG, much to the American use. It took place in Philadelphia in a hotel.
The illness takes place with an incubation period from 2 until 10 days, discomfort appears like a picture gripal of fever muscular pains, cough, difficulty to breathe, one can associate with vomiting diarrheas, morning sickness, and abdominal pain.

The Pontiac fever is produced by the same bacterium but without pulmonary affectation.

From his initial identification in 1977, numerous cases of the legionnaires' disease have been described in Canada, the USA, France, Italy and Spain, between other countries.
15 % of the cases can become mortal, and this percentage in a bacterial pneumonia in the year 2000 is very high.

The Legionnaire's disease pneumophila is the causal agent of the legionelosis. It is a bacterium like the pneumococcus that causes the normal pneumonia or the staphylococcus that produces the acne.

This bacterium is extended extensively in natural aquatic ambiences (rivers, lakes, thermal waters, etc.), being in them in small concentrations, being able to survive in very diverse environmental conditions. So that his concentration increases, containing risk for the persons, it must happen to colonize, fundamentally across the distribution networks of drinking water, water systems constructed by the man, like towers of refrigeration and distribution systems of sanitary water, where it finds suitable temperature conditions for his multiplication (25-45ºC), physical protection and appropriate nutrients.

The legionelosis is transmitted by air. It is necessary to inhale the germ that the air transports inside very small water drops. These drops come from the aerosols (pulverized water) that express the towers of refrigeration, humidifiers and cooling devices evaporativo when the water that they contain is contaminated by the legionnaire's disease.

In case of the refrigeration towers, the aerosols are thrown on the outside, with the warm air current that goes out of those, and once in the exterior, when it stops the impulse with which they were expressed, the water drops more kidlings will be transported by the wind at major or minor distance, depending on the existing meteorological conditions in this moment and of the place of the tower, being able to be transported easily several hundreds of meters.

From these facilities the Legionnaire's disease can infect the persons if the water is pulverized in the shape of aerosols so that the bacterium could be transported by the air in small drops and inhaled by the persons. Namely the route of transmission of the Legionnaire's disease is air and it has not been demonstrated that there exists any risk of falling ill on having drunk water contaminated by Legionnaire's disease.

Consequently there will be risk facilities as regards the legionnaire's disease all those that trying conditions of nesting adapted for this one, fundamentally water stagnant or retained to temperature of 25-45ºC and especially in the presence of dirt, produce aerosols that could be inhaled by the persons. For it it is recommended to do control panel in towers of refrigeration, condensers evaporativos. devices of evaporativo cooling, humidifiers, distribution systems of sanitary warm water, bubble baths, etc.

• In general in the water drops to a temperature between 20 and 40 ºC.
• Building refrigeration towers for the air conditioning.
• Systems of humidificación, TV/radio commercial and servant.
• Conductions of warm water.
• Source public.
• Other systems of circulation of warm-moderate water.

In summed up accounts, the essential factors to be born in mind favoring of the multiplication of the legionnaire's disease in the water of the towers of refrigeration are the following ones:

• HIGH TEMPERATURES, especially in the summer months.
• DIRT, which can propitiate the presence of other microorganisms (bacteria and protozoans) favoring of the multiplication of the legionnaire's disease and of his appropriate nutrients.
• INADEQUATE MATERIALS, like, wood and in general by means of cellulose.
• CORROSION AND INCRUSTATIONS, due to an incorrect maintenance of the installation and that they contribute to the multiplication of the legionnaire's disease across the nutrients contribution (iron, phosphate, etc.) and favoring the billeting of the bacterium, with what it diminishes the efficacy of the tasks of cleanliness and disinfection.

Maintenance of the systems of towers of refrigeration, wash and sterilized of the water tanks 2 times per year. The domestic deposits of warm water must be treated the same way. The water tanks outdoors must be checked periodically.

There is comprised this way the importance of which the refrigeration towers are located in strategic places, that is to say, further possibly of places frequented by the persons, so that the water drops, which they might lodge to these bacteria, settle in the soil or evaporate (dying then the bacteria), before becoming inhaled by the persons, or the aerosols are dispersed for and wind the possible maximum thing, so that the quantity of bacteria that could exist in the inhaled air was minimal and it does not contain risks for the health.

The most capable persons to the infection for Legionnaire's disease are the elders, the smokers, the affected ones by chronic bronchitis, the transplanted persons, inmunodeprimidos, or those who take corticoids as diverse reasons.