A person with active TB disease has drug resistant TB if the TB bacteria that the person is infected with, will not respond to, and are resistant to, at least one of the main TB drugs.1“Drug resistance” National Cancer Institute, http://www.cancer.gov
Drug susceptible TB is the opposite of drug resistant TB. If someone is infected with TB bacteria that are fully susceptible, it means that all of the TB drugs will be effective so long as they are taken properly. It still means that several drugs need to be taken together to provide effective TB treatment.
Drug susceptibility testing is how you find out which drugs will be effective against certain TB bacteria.
There are two ways that people get drug resistant TB.
In 2014 the World Health Organisation (WHO) estimated that 3.3% of new cases and 20% of previously treated cases of TB were of MDR TB.2“Global Tuberculosis Report 2015”, WHO, Geneva, 2015 www.who.int/tb/publications/global_report/ MDR TB is just one of the different types of drug resistant TB, and is TB that is resistant to the TB drugs isoniazid and rifampicin.
Among patients with pulmonary TB who were notified in 2014 an estimated 300,000 had MDR-TB. Globally in 2014 123,000 patients with MDR-TB or rifampicin resistant TB (RR-TB) were notified. This was just 41% of the number of estimated cases of 300,000.
There were also approximately 190,000 deaths from MDR-TB and more than half of these patients were in India, China and the Russian Federation.
The WHO is starting to look at trends focusing on the period 2008 – 2011. The current figures suggest that globally the estimated proportion of new cases with MDR-TB has not changed and remains at about 3.5%. There is more about MDR TB.
Some organisations believe that the current statistics for drug resistant TB greatly underestimate the extent of the problem.
“Wherever we’re looking for drug resistant TB we’re finding it in very alarming numbers. And that suggests to us that the current statistics that are being published about the prevalence of multi drug resistant TB are really just scratching the surface of the problem.”
Dr Leslie Shanks, Medical Director, MSF3DeCapua, J “MSF: Alarming scope of drug resistant TB”, Voice of America, March, 2012 www.voanews.com/english/news/
Another other type of drug resistant TB is XDR TB. This has been reported by 105 countries. On average an estimated 9.7% of people with MDR TB have XDR TB.
There is also totally drug resistant TB, but very few statistics are available for it.4Velayati, Ali “Emergence of New Forms of Totally Drug Resistant Tuberculosis Bacilli”, Chest, Vol 136, August 2009, no. 2 420-425 http://www.ncbi.nlm.nih.gov/pubmed/ 5Migliori, G “125 years after Robert Koch’s discovery of the tubercle bacillus: the new XDR-TB threat. Is “science” enough to tackle the epidemic?”, European Respiratory Journal, March 1 2007http://erj.ersjournals.com
There are 27 “high burden” countries. These are countries where there are at least 4,000 cases of MDR TB each year and/or at least 10% of newly registered TB cases are of MDR TB.6“Multidrug and extensively drug-resistant TB (M/XDR-TB) 2010 Global Report on Surveillance and Response”, WHO, Geneva, 2010, 15 www.who.int/tb/publications
The 27 “high burden” countries are:
Armenia, Azerbaijan, Bangladesh, Belarus, Bulgaria, China, Democratic Republic of the Congo, Estonia, Ethiopia, Georgia, India, Indonesia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Myanmar, Nigeria, Pakistan, Philippines, Republic of Moldova, Russian Federation, South Africa, Tajikistan, Ukraine, Uzbekistan, Viet Nam.
Globally there is very limited capacity to rapidly diagnose drug resistant TB. Although some new TB tests are becoming available such as the Genexpert TB test, point of care testing is still practically non existent in the areas with the highest TB burden. To overcome the problems of drug resistant TB there needs to be development of true point of care drug susceptibility tests, and their widespread implementation at affordable cost.
National TB control programs must include a universal right to treatment for drug resistant TB. It is now accepted that there is a universal right to treatment, for the treatment of HIV/AIDS. Treatment for drug resistant TB should be viewed in the same way.
There also needs to be a significant increase in the number of manufacturers of quality assured second line anti TB drugs. Action needs to be taken on this by the Global Drug Fund (GDF) and the Green Light Committee (GLC), as well as by WHO and their international partners, as part of global TB control initiatives.
At the level of global TB control there is a tension between concentrating on either drug susceptible or drug resistant TB. Some people consider that the way forward is to concentrate on drug susceptible TB, and to particularly strengthen national TB control programs, believing that this will limit or even eliminate drug resistant TB. Others consider that drug resistant TB is where the emphasis must be.
“There is a need to directly confront MDR TB and XDR TB, whereas emphasis in the past has been on strengthening TB control programs per se, believing that we could thereby control the problem of MDR and XDR TB.” 7IOM (Institute of Medicine). “Addressing the Threat of Drug-Resistant Tuberculosis: A Realistic Assessment of the Challenge: Workshop Summary” The National Academies Press, 2009, 12
At local, national and global level, the resources and the commitment need to be found to do both. National TB control programs need to more effectively find and treat people with drug susceptible TB, and they then won’t develop and spread drug resistant TB. There is also a need to find people and provide treatment for drug resistant TB, to not only save their lives, but also to prevent them transmitting drug resistant TB to others. There is no reason why this should not be possible.
There is also a need for higher income countries which are not so directly affected, to play their part at a global level in combating drug resistant TB. In 2015 a plan was published by the United States to combat drug resistant TB, both within the United States and in other countries.
“Today MDR TB spreads unchecked in most of the world. It is fueled by poverty at the individual and family levels, – limiting access to effective treatment – and at the regional and national level, where under resourced governments lack the capacity to tackle this disease.” 8Keshavjee, S., Farmer, P.E. “Time to put boots on the ground: making universal access to MDR-TB treatment a reality”, Int J Tuberc Lung Dis, 14(10), October 2010, 1222-1225 http://www.ingentaconnect.com
Drug resistant TB 2014 Supplement Global Tuberculosis Report, WHO, Geneva, 2014 www.who.int/tb/publications/global_report/en/
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|1.||↑||“Drug resistance” National Cancer Institute, http://www.cancer.gov|
|2.||↑||“Global Tuberculosis Report 2015”, WHO, Geneva, 2015 www.who.int/tb/publications/global_report/|
|3.||↑||DeCapua, J “MSF: Alarming scope of drug resistant TB”, Voice of America, March, 2012 www.voanews.com/english/news/|
|4.||↑||Velayati, Ali “Emergence of New Forms of Totally Drug Resistant Tuberculosis Bacilli”, Chest, Vol 136, August 2009, no. 2 420-425 http://www.ncbi.nlm.nih.gov/pubmed/|
|5.||↑||Migliori, G “125 years after Robert Koch’s discovery of the tubercle bacillus: the new XDR-TB threat. Is “science” enough to tackle the epidemic?”, European Respiratory Journal, March 1 2007http://erj.ersjournals.com|
|6.||↑||“Multidrug and extensively drug-resistant TB (M/XDR-TB) 2010 Global Report on Surveillance and Response”, WHO, Geneva, 2010, 15 www.who.int/tb/publications|
|7.||↑||IOM (Institute of Medicine). “Addressing the Threat of Drug-Resistant Tuberculosis: A Realistic Assessment of the Challenge: Workshop Summary” The National Academies Press, 2009, 12|
|8.||↑||Keshavjee, S., Farmer, P.E. “Time to put boots on the ground: making universal access to MDR-TB treatment a reality”, Int J Tuberc Lung Dis, 14(10), October 2010, 1222-1225 http://www.ingentaconnect.com|