Thursday, October 6

Legionella: experts warn that the summer heat advances the season


the time of legionellosis in Spainthe disease caused by lung infection by the bacteria legionella pneumophilabegins at the end of September and has its peak in October and part of November, if it is warm.

The reason is explained by Ana Carmen Aguirre Unamuno, expert Technical Manager in legionella at the environmental control company Rentokil: “The main source of pollution is the cooling towers of buildings and large surfaces, since they usually stop at the end of summer and, with the heat, the water they carry can lead to a growth bacterial”.

After yes in october or november there are the typical hot weeks, are reactivated with the already contaminated water, and this is expelled through the upper part of the towers in the form of an aerosol. And that spray can contain the strains of legionellait goes down to street level, where we breathe it“, continues Aguirre.

The expert explains that the aerosol droplets less than 5 µ (thousandth of a cm) are aspirated and travel directly to the lungs, where infection can start. Aguirre also clarifies that the lung is the only route of infection, so there is no need to fear drinking water.

The effect of a hot summer

But this year legionellosis, a serious disease that can be fatal, has advanced its season: in Cáceres this August there have been 15 cases and four deaths for the possible presence of legionella in fountains or hydrants.

and a few days ago the Hospital Clínic de València has been forced to cut off the water from a plant for a case of legionellosis in a patient: “It is an in-hospital case, which makes it especially dangerous for other patients, since the focus is inside,” explains Aguirre.

The person in charge of environmental control believes that it is very possible that the intense and prolonged heat of these spring and summer have caused the water from fountains, hydrants and even building installations to contain populations of legionella.

The reason is that the legionella it can find its habitat in the dirt accumulated during the summer and in the ambient heat, since it grows between 25º and 45ºC, with an optimum around 35ºC.

The problem may be in pockets of stagnant water from tanks and heaters that have had little circulation, although this bacteria can also grow on the rusty interior walls of pipes in poor condition; The fact is that with climate change this type of contamination is more frequent and the legionella forward each year more his season and attacks with more intensity.

In fact, Since 2015, the WHO considers climate change to be the main cause of the increase in cases of legionellosis in the First World. According to data from the European Center for Disease Control (ECDC), In 2018, a total of 11,343 cases of legionellosis were registered in Europewhich is 57% more than in 2007.

In Spain, the data can also be considered alarming, since the ECDC detected 1,513 cases in the same year, slightly more than double those registered in 2011. With this figure, Spain was placed at the head of legionellosis cases in Europe.

In Cáceres and Valencia, most likely cases of contagion have occurred by inhaling the aerosol formed by the water droplets launched by a fountain or an irrigation sprinkler, and in Valencia it is possible to think of a shower of hot water that comes from boilers that have not been used during the summer, where the legionella has proliferated.

But there are other delicate systems that should be watched, such as the wet saunas of gyms and spa centers, because aerosols and heat abound in these spaces. Another possible source, “although less probable”, clarifies Aguirre, are the heat pumps that work in duct systems, since water can condense during the summer in which the bacteria then proliferate if we use the pump in the autumn to release hot air .

Tips to avoid risks at home

If we have an air conditioning system at home that works with air distribution through ducts -either in a false ceiling, already in exposed brick-, or we work in an office, restaurant or any other business that is air-conditioned by this system, we must to ensure that the following conditions are met, in order to reduce the risk as much as possible:

During the summer the conditions that favor the colonization and multiplication of legionella in the ducts. That is to say that the environmental temperatures have not been higher than 25º, and above all that it has not been possible to establish water, or that substrates capable of collecting humidity and at the same time that they can serve as food have not accumulated.

For this, it is necessary that we ensure that regular cleaning and disinfection are carried out in our home or in our workplace, especially before the start-up of an installation that has spent a long time without working. In this regard, it is advisable to be especially scrupulous in places where there is a sensitive population, such as hospitals, medical centers and centers for the elderly.

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