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   Legionellosis / ATHISA MEDIO AMBIENTE

Brief History of Legionella
Also known as Legionese disease. It acquired its name in 1976. In that year there was an outbreak of pneumonia among the participants of a Convention of the American Legion in Philadelphia. USA. On 18th January 1977, scientists identified a previously unknown bacterium as the cause of the mysterious infection of legionese disease, a bacterium that was called legionella or Legionella pneumophila.

How and where it is spread
Water and warm temperature are this bacterium’s great allies. It spread from rivers and lakes to those installations that require constant water storage. The way of transmission of legionella is through the air. The disease is contracted through sprays breathed out from the drops of waters in the cisterns. An air conditioning refrigeration tower works as follows:

List of installations where legionella can develop:

Instalations most a risk
• Refrigeration towers and evaporating condensers
Sanitary hot water systems with accumulators and closed circuits
Systems of climatised water in constant movement and recirculation through high speed jets or air injection (spas, Jacuzzis, swimming pools, therapeutic baths, hydro-massage baths, jet treatments, others.)
Industrial central humidifiers

Instalations at moderate risk
• Cold water interior systems for human consumption (tubes, deposits), cisterns and mobile deposits and hot water without closed system.
• Equipments to cool water by evaporation through pulverisation.
• Humidifiers
• Ornamental fountains
• Watering systems by aspersion in cities
• Fire protection water systems
• Refrigeration element by spray in the open air
• Other apparatus that accumulate water and can produce spray.

Others installations that can be infected
• Respiratory therapy equipment
• Respirators.
• Nebulisators
• Other medical equipments in contact with respiratory ways

Lets see the process in a sanitary system of hot and cold water with accumulators and closed circuits :


Five strategies against legionella
According to the Spanish ministry of Health and Consumption, there are five strategies to follow for the maintenance of installations where legionella can break out. We satisfy each of them :

Plans and measurements

A plan is drown up showing the components of each installation, which is updated every time a modification is made.
The plan will show the critical points or zones where water samples must be taken.

Evaluation
We revise and examine every installation to insure its correct functioning, establishing critical points, parameters to measure and the procedure to be followed, as well as the periodicity of each activity.


Water control
The quality of water is insure with products in the correct quantity and procedure, as well as the introduction of physical, chemical and biological control parameters, the methods of measurement and the periodicity of these analyses.

Cleaning and disinfection
To insure that every installation function safely, we thoroughly clean and disinfect it, establishing clear procedures, products to be used and quantities, precautions to bear in mind and the periodicity of each activity.

Record book
A record of maintenance of each installation is supplied which contains a record of all the incidences, activities carried out, results obtains and the date of starting and stopping installations including the reasons.


 



The bacterium responsible

This is an aerobic bacillus belonging to the large family of “Legionellaceae” with 30 species and fifty known as serogroups.

Legionella pneumophila causes 90% of infections. It appears in dump conditions and temperature between 32º and 45ºC, 35º C and 37ºC being the ideal thermic range for its growth. Although it resists cold, if it is subject to more than 60ºC, it is destroyed. It is also destroyed by a mixture of 1% formaline, 70% ethylic alcohol, 10 ppm of iodine, 0,125% glutaraldehide and 1:8000 solution of quaternary ammonium.

In moving water, it can survive for more than one year. It remains for 5 or 6 months in refrigerated liquid culture.


Stages of pulmonary infection by legionellosis


The most serious cases of legionellosis occurred in Murcia (Spain) in July 2001.

The result was 6 deaths and more than 600 infected. The focus was found in the Morales Messenger Hospital.
Legionellosis can cause diseases in men:

La legionela es capaz de producir dos enfermedades en el hombre:
• Pneumonía
• Pontiac fever

Cases of legionella disease occurs every year in refrigeration towers of Spanish hospitals and health centres. As with many other diseases, it is especially aggressive in older people causing death from serious pneumonia. For this reason we recommend inspecting the refrigeration installations at regular intervals.

Links
Real decreto (Spanish Law on legionellosis from the Ministry of Health and Consumption)

 

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