It is still one of the ten leading causes of death in the world. Yet it can not only be cured, but also prevented.
Tuberculosis is one of those infectious diseases that are wrongly considered outdated. In fact, according to data released by the World Health Organization (WHO) on the occasion of World Tuberculosis Day, this disease is still one of the ten leading causes of death in the world and, in 2016 alone, led to almost 2 million people dying and recorded over 10 million new cases.
It is therefore advisable to know better the problem, the causes, the symptoms and the strategies to better deal with it.
The numbers of the phenomenon
Even today there are many countries with high tuberculosis endemic, i.e. countries in which the disease reaches an estimated annual incidence of over 100 cases per 100 thousand inhabitants. These are mostly developing countries, also because tuberculosis is a disease strongly associated with living conditions: poor hygiene, poor diet or even malnutrition and in general poor health facilitate the lowering of immune defenses and the risk of an epidemic.
Although in the European region of the WHO and in Italy there is a low percentage of cases (about 3% of the world total), the disease is still considered a public health problem, in view of the increase in population mobility and the spread of forms of tuberculosis resistant to anti-tuberculosis drugs and therefore more difficult to treat.
Italy is among the countries with a low incidence of the disease (ie with less than 20 cases per 100 thousand inhabitants): in particular, the most recent data (present in the joint document of the ECDC, European Centre for disease prevention and control, and WHO Europe) reveal that in 2016 4,032 cases of tuberculosis were notified, with a slightly decreasing incidence compared to the last 10 years. As many as 62% of these cases involved immigrants. Also for this reason, in February 2018, specific guidelines for the control of tuberculosis among immigrants were published, as part of the National Migrant Health Guidelines Program.
The cause is a bacterium
Tuberculosis, also known by the acronym TB, is an infectious disease caused by various strains of the genus of mycobacteria, including in particular Mycobacterium tuberculosis also called Koch’s bacillus.
Infection can occur by transmission from a sick individual by air, through droplets of saliva emitted with a sneeze or cough. Possible, but extremely rare, are cases of transmission from mother to child during pregnancy.
However, it is not enough to come into contact with the bacterium to get sick: in a large percentage of cases (about more than 80%) the immune system manages to make it harmless, building around it a sort of “barrier”, the so-called tubercles (from which the infection takes its name), a sort of small and hard nodules. The bacteria, therefore, remain in the body but without causing disease and we speak, in this case, of latent tuberculosis infection. A person with this infection is neither sick nor contagious, but can eventually become so when his immune defenses suffer a drastic decline.
When, on the other hand, they manage to prevail, mycobacteria through the blood can reach and affect all organs and systems of the body. The most common form of TB, however, is the one that involves the lungs and the respiratory system: bacteria progressively destroy the pulmonary alveoli, the small sacs located at the end of the bronchioles (the thinnest branch of the bronchi), in which the exchanges between oxygen and carbon dioxide take place. As a result, breathing becomes increasingly difficult.
It must be said that those who are HIV-positive and are infected by mycobacteria get sick with tuberculosis much more easily than those who, although infected, are not HIV-positive, because the HIV virus drastically weakens the immune system (tuberculosis is also the main cause of death among HIV-positive people).
Symptoms of tuberculosis
Tuberculosis disease is manifested by:
- the appearance of fever and chest pain
- increased sweating
- weight loss
- lack of appetite.
Surely, however, the most obvious and annoying symptom is persistent cough with phlegm. Over time, in some cases, traces of blood are also excreted in the sputum.
Those who have only a latent tuberculosis infection do not show any particular symptoms, except the positivity to the so-called Mantoux test.
How the diagnosis is made
The most common test for the diagnosis of tuberculosis infection is precisely the Mantoux test: tuberculin, a purified protein obtained from the bacterium responsible for the disease, is injected into the skin of the forearm. It is therefore necessary to wait 48 hours and observe the reaction of the skin to the substance: if a reddened and hardened area forms around the injection site, it means that the bacterium is present in the body, but not necessarily that the person is really sick.
In these cases, a further investigation is carried out: considering that the organ generally most affected is precisely the lung, a chest X-ray is performed which allows to highlight any anomalies in the pulmonary aspect typical of tuberculosis.
However, according to international guidelines published in 1995, the early diagnosis of the disease is carried out by analyzing the person’s sputum in the laboratory, looking for the presence of Koch’s bacillus with a microscope.
How do we cure it
Tuberculosis therapy is based on the use of antibiotics to be taken daily. Currently those used are:
- isoniazid
- Rifampicin
- ethambutol
- pyrazinamide
- streptomycin.
They are prescribed in different combinations, both for attack therapy (which usually lasts at least two months) and for maintenance therapy. It is the doctor who decides the most suitable combination of antibiotics for the individual case and, even if already after 24 hours from the start of treatment you are no longer contagious, the therapy should be continued for at least six months.
Treatment with anti-tuberculosis drugs should be followed scrupulously and closely monitored with periodic checks. According to the international guidelines already mentioned, in fact, it is good to follow the so-called DOT, or the therapy observed directly, from the initial letters of the English words Directly Observed Therapy.
The DOT provides that the patient is constantly followed by a health professional, for all the months of therapy, who ensures the correct and regular intake of drugs, the effects and effectiveness of the same and the course of the disease. It is a therapeutic strategy that aims to avoid the establishment of antibiotic resistance. In addition, if the DOT is followed correctly, the TB treatment period typically lasts about 6 months.
Even those who have a latent tuberculosis infection are subjected to an antibiotic prophylaxis of a few months, to prevent the mycobacteria present in the body from reactivating and triggering the disease.
The problem of resistant tuberculosis
Accomplices incomplete or incorrectly administered therapies, the antibiotic resistance drug of some bacteria is now a reality. Even in the field of TB we are witnessing, in recent decades, the spread of forms of tuberculosis disease that resist the antibiotics traditionally used.
One of the most dangerous forms and, according to the WHO, now present in every area of the world is MDR-TB (multidrug resistant tb), a form of tuberculosis resistant in particular to two first-line antibiotics, rifampicin and isoniazid. It therefore requires longer therapy and with second-line antibiotic drugs (such as fluoroquinolones, capreomycin, kanamycin, amikacin, cycloserine, clofazimine).
There are cases, fortunately still quite rare, of Xdr-tb, that is tuberculosis and xtensively drug-resistant, that is also resistant to numerous second-line anti-tuberculosis drugs and which, as you can guess, becomes very difficult to treat.
There is also the vaccine
There is also a specific vaccine against tuberculosis, called BCG, because it uses the bacillus of Calmette-Guérin, an attenuated bacterium deriving from a strain of Mycobacterium bovis which, injected into the body, induces a reaction by the immune system. Unlike other vaccines, however, it does not offer total protection and is increasingly less effective in adults.
However, vaccination is widely used (and also mandatory) in several countries around the world, in particular those at high risk of tuberculosis, especially in infants and children, where it is still of considerable importance.
In our country vaccination is mandatory (according to the decree of the Republic 465 of 7 November 2001) in two cases:
- infants and children under 5 years of age, with a negative tuberculin test, living in cohabitation with or having close contact with people with contagious tuberculosis, if the risk of infection persists
- health workers, medical students, student nurses and anyone who, for any reason, with a negative tuberculin test, operates in healthcare environments at high risk of exposure to multidrug-resistant strains or who operates in high-risk environments and cannot, in case of cuticonversion (ie positive response to the Mantoux test), be subjected to preventive therapy, because it presents clinical contraindications to the use of specific drugs.
Joycelyn Elders is the author and creator of EmpowerEssence, a health and wellness blog. Elders is a respected public health advocate and pediatrician dedicated to promoting general health and well-being.
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