After the publicizing of the deadly XDR TB (Extensively drug-resistant tuberculosis) epidemic among the HIV patients in the town of Tugela Ferry (South Africa), scientists and doctors were warning about the emergence of even deadlier forms of the bacterium which causes tuberculosis. And in 2009, they were proved right. An even more deadlier form of the bacteria was discovered in Iran, which was named as TDR TB (Totally drug-resistant tuberculosis). Even XDR-TB is almost impossible to treat. Out of the 53 patients who were infected during the 2006 Tugela Ferry epidemic, 52 died within a few days. The TDR version is even more deadly and survival rates are much lower than that of XDR TB.
The first mutated version of the TB bacterium was discovered during the 1990s. It was termed MDR TB (Multi-drug resistant TB). MDR TB patients develop resistance with all the first line drugs ((Isoniazid, Rifampicin, Ethambutol, Pyrazinamide, and Streptomycin) used for the treatment of TB. Therefore, they should undergo treatment using the more toxic second line drugs (A total of 7 drugs in six classes: Oﬂoxacin, Moxiﬂoxacin, Kanamycin, Amikacin, Capreomycin, Para – Aminosalicylic acid, and Ethionamide). But when the patient develops resistance even to these second line drugs, the condition becomes almost impossible to treat. If the resistance is developed for one or more of the second line drugs, then the condition is called XDR TB (XDR TB was first described in the year 2006). If the resistance is developed for all the six classes, then the condition becomes TDR TB (TDR TB was first described in the year 2009).
There is no effective treatment regimen available to TDR patients. All they can do is to eat nutritious food and engage themselves in activities such as medication. The main reason for the spread of TDR TB is the erratic treatment offered to MDR and XDR TB patients by less qualified doctors. The misuse of second line drugs mutates the TB bacteria and as a result, it attains resistance to all the first line and second line drugs.
A stunning example of TDR TB epidemic resulting from misuse of second line drugs is the 2011 Dharavi TDR TB epidemic. A total of 4 patients were diagnosed with TDR TB in the slum area of Dharavi (Mumbai, India). All of them developed drug resistance as a result of misuse of drugs, and their condition worsened from normal TB to MDR TB and then to XDR TB, contracting TDR TB in the end. Of the 4 patients, 3 were female (ages: 20, 31 and 37) and one was male (57 years old). The fact that all of them first depended on private doctors (most probably quacks) for treatment says something about the lack of availability of quality healthcare in the area.
Right now, the TDR TB is confined to a handful of cases and isolated in a few pockets. But the possibility cannot be ruled out for an all out epidemic, especially since the TB bacterium is highly contagious. Therefore, medical research should be encouraged and carried forward, and we should find at least one single drug which can effectively treat TDR TB.