It should be important for everyone being aware of the different risks that can affect our health. Because of this, throughout the following lines we are going to talk abouttwelveaspects about legionella that you should understand, from what it is to how it can affect humans.

1.     What is legionella?

Legionella is an environmental bacteria, which can cause deadly diseases such as legionellosis or pneumonia. Therefore, it is important for your health to know that an outbreak of legionella can happen as a result of different causes, and thebacteriacan spread through the common use of water circuits such as Jacuzzis or even air conditioners, for example.

2.     It is dangerous?

Legionella pneumophila is the second organism responsible for severe community pneumonias.It might require the infected individualto stayin the intensive care unit.It can be caused by streptococcus pneumoniae, and when these subjects attend hospitals presenting the symptoms these usually includeacute respiratory failure and even septic shock.

3.     Who are the most affected?

Between 75% and 80% of all reported cases are people over 50, and between 60% and 70% are men. There are also risk factors for extra-hospital or travel-associated legionellosis: smoking, excessive alcohol consumption, lung diseases, immunosuppression and chronic respiratory or renal diseases.

4.     Incubation

The legionnaire’s disease has an incubation period of 2 to 10 days.The initial symptoms are fever, loss of appetite, headache, malaise and lethargy. Some patients also report muscle pain, diarrhoea and confusion.

5.     Is there a vaccine?

Currently, there is no vaccine available against legionellosis.

6.     Can it be spread through air conditioners?

In large stores such as shopping centres or malls, this is a possibility, while in the air conditioners of homes is not that usual. The difference between the two casesis the way of cooling the compressed gas. Domestic systems use atmospheric air, while industrial systems use water. Therefore, if the legionella is present on the water, the risk of an outbreak is very high.

7.     How does it affect us exactly?

According to studies published in the journal Science, the bacteria deliberately infiltrate the cells of the human immune system and inject a large amount of proteins that interfere with normal cellular processes.

8.     Where does it happen?

It can happen anywhere around the world.

9.     What are the main sources of contamination?

The main sources of contamination from which the bacteria spreads and infect humans are water storage tanks, heating and hot water systems, cooling towers, evaporative condensers and, in short, those systems that keep the water at an optimal temperature for the growth of bacteria. However, any element that can produce aerosols, including faucets, showerheads, fountain jets, sprinkler irrigation systems or medical aerosol therapy equipment, can be a source of contamination.

10. At what temperature does it grow?

It is very resistant in its natural habitat, capable of surviving in very varied physical-chemical conditions and its optimal temperature for growth is 35 to 37 degreescelsius but it is capable of multiplying between 20ºC and 45ºC.

11. At what temperature is it destroyed?

At temperatures below 20ºC it enters a dormant state and at 70ºC it is destroyed.

12. Who could be more exposed?

Labour activities with risk are those such asagriculture, forestry or gardening. Also water supply, sanitation activities, waste management and urban cleaning, maintenance activities,sanitary activities and laboratories, among others.

In order to prevent these sort of outbreaksof bacteria in water, which can affect you and your community, it would be ideal to measure water quality and develop a legionella risk assessment. This can be useful if you don´t know how to act against this problem or if you want to be precautious.