Tuberculosis: what it is, who it affects, how it spreads, symptoms, treatments

Tuberculosis: what it is, who it affects, how it spreads, symptoms, treatments

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OfElena Meli

It is important to check for positivity to the bacterium before undergoing therapy. 1 in 3 patients does not respond to the most used antibiotic. Encouraging prospects from a new vaccine

It is an almost forgotten disease, which we do not think can concern us: the tuberculosis (TB) it is associated with a distant past, or with low-income countries. Instead, it is still a current problem: in Italy since the 1950s, new cases have progressively decreased, but more than 2 thousand every year. Not to mention that the trend the continuous decline in the number of patients seems to be reversing: the World Health Organization (WHO) has just underlined that in Europe during the pandemic period There have been more deaths from TB than expected and in the world i infections are growing as well as cases of resistant disease to rifampicin, one of the most used drugs for treatment, currently ineffective in approximately 1 in 3 patients.

TB remains latent, often forever

«We are used to infectious diseases that appear immediately after infection, with TB this is often not the case – explains Federico Gobbi, director of the Department of Infectious and Tropical Diseases of the Irccs Sacro Cuore Don Calabria of Negrar -. When you come in contact with Mycobacterium tuberculosis (or Koch’s bacillus), the responsible agent, in 90% of cases the disease does not develop but a sort of balance is created with the immune system: the germ enters the cells and thanks to the body’s defense reaction it is ” walled up” in the lung tissue (in granulomas where bacteria and immune cells are found, ed.). TB therefore remains latent, often forever. In the 10% of infected people who develop the disease, this happens in half of the cases within 1-2 years of infection, otherwise even after many, many years.”

Who strikes

This explains why in Italy most of the new TB cases concern migrant population or elderly people, who perhaps became infected many years before. «Migrants have higher rates of illness because they come from areas where TB is more widespread, but they often become infected during the journey or in Italy, because they live in poor conditions», specifies Gobbi. «The elderly, on the other hand, get sick because the “wall” around the bacillus with which they perhaps came into contact 60 or 70 years ago crumbles following immunosuppressive therapy, for example to treat a rheumatic or oncological pathology».

Be careful with immunosuppressive therapies

When the immune system weakens, due to therapy, a concomitant disease, advancing age or other reasons, the barrier that had been raised around the Mycobacterium fails, the bacterium frees itself and the symptoms of pulmonary TB with low-grade fever, cough that doesn’t go away, tiredness. «For this reason, before starting immunosuppressive therapies in any patient, it is advisable to verify thepossible positivity to the bacillus» adds the expert. «If so, to avoid letting the bacterium escape from the “broken wall”, a therapy is used that kills it, generally based on rifampicin and isoniazid for three months. However, it is important to underline that people with latent TB are not sick, and above all they are not contagious: only those who have the “reactivated” disease are, because at that point the bacterium can be released into the environment and breathed in by others.” The full-blown disease can cause mild symptoms even for months, so the diagnosis can arrive late; Recognizing TB is essential to treating it with the right antibiotics, which however must be taken for long periods, of at least six months, and on a regular basis also to prevent resistance from appearing.

1 in 4 people carry the bacterium

«The cases of multi-resistance different types of drugs are constantly increasing and there are fears that they could become a serious public health problem in the coming years, also because during the pandemic there was a notable drop in diagnoses and therapies, especially in low-income countries and we expect an increase in patients in the future”, observes Gobbi. «Already today, however, tuberculosis is the infectious disease caused by a single microorganism that causes the greatest number of deaths in the world, around one and a half million per year. The fact that it mainly concerns poor countries should not leave us indifferent, because the Covid-19 pandemic should have taught us how interconnected the health of the inhabitants of the entire planet is. Estimates from the World Health Organization speak of an enormous pool of people infected by Mycobacterium, around two billion in the world: it means that 1 in 4 people, even if they will not infect anyone and will never get sick, are carriers of the bacterium.

In Italy

This is also why the efforts to arrive at a new vaccine are more than necessary: ​​to date the only one available remains Bcg (Calmette-Guérin bacillus, a live attenuated vaccine that has now been developed over a hundred years ago, in 1921, ed) which helps just to reduce complications of tuberculosis but is not very effective in preventing the disease and is only used in low-income countries where tuberculosis is widespread.” This is not the case withItaly, where it is mandatory only in risk categories such as children under five years old who are negative for the bacterium and who live with people with active disease or healthcare personnel; However, it is advisable not to let your guard down.

Encouraging prospects from a new vaccine

Transmitting TB is not easy: those who have been infected must have the lung disease in the active phase, a high bacterial load and not be under treatment, plus they must find themselves in situations with little or no air exchange. Despite this, having a vaccine to prevent the spread of the bacillus is an objective considered fundamental by the WHO, which has announced its intention to create a Tuberculosis Vaccine Accelerator Council to quickly arrive at an effective product: this is also why the positive data of one experimentation of phase 1 of a vaccine that combines various Mycobacterium proteins and is prepared in a way that can be stored at high temperatures (around 38°C) for months, which is no small factor considering the usefulness of such a vaccination in countries where cold storage cold would be problematic. The arrival at the clinic is not around the corner, but the studies continue.

March 23, 2024 (modified March 23, 2024 | 12:21)

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