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Tuberculosis (TB) is one of the most prevalent bacterial infectious diseases worldwide. World Health Organisation (WHO) estimates that every third person in the world is now infected. Mycobacterium tuberculosis, the microorganism causing the infection is transferred through air. TB usually causes lung infection, but can also affect kidney, brain and spine. If untreated, it can lead to death.
Tuberculosis is a global health threat
Twenty years ago, WHO declared the spreading TB infection as global emergency. Significant funds and resources were invested into the management of TB and development of novel drugs but, as it stands now, TB became even more dangerous and widespread.
Multidrug resistance in TB is defined as the lack of response to the treatment by two powerful antibiotics – rifampicin and isoniazid. These antibiotics are used as a first line of treatment. Resistance can develop as a result of using just one drug for the treatment of TB infected patients (monotherapy) and poor adherence to drug regiments. Ones MDR strain emerges, it can be transmitted within the community. MDR resistant TB has to be treated with the second line therapy which involves more drugs, longer duration of treatment and lower success rate.
Multidrug resistant and extremely drug-resistant forms of tuberculosis
MDR form of TB was very unusual 20 years ago, but now it is reported virtually everywhere. In some regions of Central Asia and Eastern Europe MDR represents a very significant proportion of new TB cases (9 to 32%). But the most alarming recent development is the emergence of new, so-called extremely drug-resistant (XDR) form of TB. This form does not respond to rifampicin, isoniazid, fluoroquinolones and at least one of the injectable second line treatments. Such level of resistance makes this form of TB practically untreatable. 84 countries around the globe have already reported at least one case of XDR TB.
Global efforts and new political vision are needed to tackle the emergence of untreatable tuberculosis
In the modern world, drug discovery and development is a domain of multinational pharmaceutical companies. The business is money driven – successful drug can be extremely profitable and bring billions of dollars to the inventors. Unfortunately, drug development is also a very expensive process. On average, introduction of one new successful drug costs well in excess of US$ 1 billion these days. When starting a new drug development process, pharmaceutical companies must be sure that their huge investments will be at least compensated by the future sales. Unfortunately, this is not the case when disease is more common in poorer countries.