Legionellosis, the bacteria that sneaks into refrigeration systems

An outbreak in Cáceres with at least two deceased and a dozen affected currently puts legionellosis, an environmental disease that varies in severity, from mild conditions with fever to pneumonia that can be fatal.

According to World Health Organization (WHO), these are the main characteristics of this disease which is present practically all over the world.


It originates from bacteria Legionella pneumophila which was first described in 1977, as the cause of an outbreak of severe pneumonia recorded the previous year in a convention center in the United States.

This bacterium and other related species are often found in lakes, rivers, streams, hot springs, and other water systems.


It is associated with outbreaks related to poorly maintained artificial water systems, particularly cooling towers or evaporative condensers used for industrial refrigeration and air conditioning systems, hot and cold water systems in public and private buildings, and whirlpool facilities.

That is why it is especially dangerous in places such as hospitals, with vulnerable people, or hotels, with a high concentration of the public.


The most frequent way of transmission of Legionella is the inhalation of contaminated aerosols from cooling towers for air conditioning, hot and cold water systems, humidifiers and hydromassage installations.

Infection can also occur by aspiration of contaminated water or ice, especially in vulnerable hospitalized patients, or by exposure of the newborn during water births.

There is no direct transmission from person to person.