One death and several hospitalized. At the moment these are the official figures of the microepidemic of legionellosis underway in a well-defined area (it is always worth remembering this) of Milan, in the San Siro district. Fears are particularly high for the elderly and immunosuppressed people, who are more exposed to possible complications of the condition.
But what are we talking about? Here, in summary, is how the pathology of the respiratory tract caused by a particular germ, la., arises and develops Legionella pneumophilaso called because of its tendency to develop in the lungs.
Identikit of the bacterium
Legionella is naturally present in environments where water is present. It manages to proliferate at temperatures between 20 and 50 degrees, becoming potentially dangerous for human health precisely because it develops in quantity. Unfortunately, it happens that infections linked to the bacterium represent, with their “resurgences” like the one we are observing, a concrete challenge for public health.
To be precise, talking about a single germ is not correct, given that there are many variations of the bacterium, which lives without causing particular problems to the human organism, as we have seen, especially in rivers and lakes at not too low temperatures. The situation changes profoundly when legionella reproduces in large quantities inside pipes or routes where conditioned air is spread within environments. In these conditions, in fact, the germ replicates at great speed, forming a sort of invisible “film” along the water cooling columns and other piping systems, especially if rust residues are present.
It is important to remember one thing: the disease is not transmitted from person to person. The spread of the bacterium occurs through inhalation by breathing particles of nebulized water coming from a contaminated system or equipment.
What the infection looks like
The symptoms of legionellosis normally resemble those of common bronchopneumonia and appear within a period of two to ten days from the moment of infection. The affected person experiences fever and a strong cough, which can be dry and then also induce the production of mucus. In some cases these problems are associated with poor kidney function and other general ailments, such as headaches and muscle pain, tiredness, loss of appetite and, occasionally, diarrhoea.
Since the symptoms are quite general, suspicion of the disease can be confirmed through tests on blood and bronchial secretions.
In general, therefore, the diagnosis is ascertained through a radiological examination of the chest and the search for antigen Legionella pneumophila in urine and culture of Legionella on a respiratory sample. There are obviously also other tests that can be requested, case by case, by specialists.
How to treat it and who is at risk
Contracted through inhalation or aspiration of contaminated aerosol, legionellosis can therefore potentially cause serious infections of the respiratory system which present with symptoms that can initially manifest themselves in a similar way to those of severe pneumonia, leading in some cases to serious complications. For this reason it is necessary to immediately think about targeted therapies on a case-by-case basis, starting with antibiotics active on the germ, which in many cases prove to be extremely effective, so much so that the infection passes without leaving any sign. These drugs can be combined with breathing support strategies as well as other medicines, such as anti-inflammatories.
In terms of attention to be paid, we remind you that the so-called immunocompromised subjects are at particular risk, i.e. they have a lower defensive response than normal, which can happen especially in elderly people, or in those suffering from oncological or chronic diseases. Going through the data relating to 2022 for Italy, we also realize that the elderly are most affected in the event of full-blown cases. Statistics say that based on age distribution, more than 70% of those affected are at least 60 years old and the incidence increases with age, reaching the maximum value of 169.7 cases per million inhabitants in the age group of 80 years or more.
Finally, those who smoke appear more exposed to contracting this infection due to the lack of the “filter” action of the bronchi on the inhaled air.
