Sunday 13 December 2009, 23:03

Tuberculosis: a threat still alive

Recent data on the epidemiology of tuberculosis

Tuberculosis: a threat still alive

Tuberculosis or TBC is a chronic bacterial infectious disease which has been known for hundreds of years, but still affecting many people today all over the world.


Despite of the great advances in our knowledge of its epidemiology and pathogenesis and the development of effective diagnostic, preventive and therapeutic techniques and strategies, tuberculosis is still a widespread threat and its eradication is far from becoming a reality.


The WHO estimates that, still today, 8-9 million people worldwide fall ill with active tuberculosis each year and about 2 million die from it. And these number will continue to increase over the next years, as a consequence of both the spread of immunosuppressive diseases and the development of multidrug-resistant tuberculosis (MDR tuberculosis) all over the world.


Tuberculosis is a contagious disease spread through the air. It is transmitted through airborne droplets from the coughs and sneezes of people affected by the active (symptomatic) form of the disease. The inhalation of a small number of TB germs is sufficient to cause infection. However most of the infected people neither become ill nor transmit the organism: the immune system acts as an effective barrier against the onset of the full-blown symptomatic disease, by insulating the mycobacteria from contact with body fluids and tissues.


It is only when the immune system is weakened for some reason that active tuberculosis may develop. That's why the most important risk factors for active tuberculosis are those related to the suppression of the immune system function: for example medical conditions such as AIDS, diabetes and malnutrition, or medical treatmens such as long-term corticosteroid therapy. Besides the medical factors listed above, it is necessary to consider risk factors related to the life conditions: for example stress, alcohol, poor hygiene, poverty and homelessness.


As regards the incidence of tuberculosis, according to the WHO estimates, the highest morbidity and mortality rates occur in the poorest countries: sub-Saharan Africa, South-East Asia Region and Eastern Mediterranean Region. In has been estimated that about one third of the world's population is currently infected with Mycobacterium tuberculosis and that 10% of infected people contract the active form. Half of the patients with the full-blown symptomatic disease die from it.


The WHO's efforts to control tuberculosis are on the agenda, although they seem to be still far from achieving the complete eradication of the disease. The indiscriminate use of antibiotic drugs and the spread of immunosuppressive diseases (in particular HIV infection) have led, respectively, to the development of multidrug-resistant tuberculosis and to the increase of the number of high-risk patients: two aspects that contribute to the widespread of untreatable tuberculosis.


By Chiara De Carli

Category: Medical

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