RESEARCH ON TB

XDR PLUS TB


The World Health Organisation considers all the cases of "totally" drug resistant TB to be XDR TB because they all satisfy the criteria for XDR TB.

As there is currently some considerable confusion being caused by all the different names, one possibility would be to refer to these cases of drug resistant TB as being "XDR plus" TB, meaning cases of XDR TB with additional unspecified resistance. This would be similar to having MDR plus TB for cases of MDR TB where there was additional resistance.
How many cases are there each year of drug resistant TB?

In 2011 the World Health Organisation (WHO) estimated that there were globally 310,000 cases of MDR TB among those cases of pulmonary TB that were reported to them

It was also estimated that in total there were 630,000 cases of MDR TB among the world’s 12 million prevalent cases of active TB. The number of prevalent cases of MDR-TB is important as it directly influences the active transmission of strains of MDR TB.11 (For more about TB incidence and prevalence see the TB statistics page.)The WHO is not able to provide an answer as to whether the number of people with MDR TB is increasing, decreasing or stable, either regionally or globally.12 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, MSF13

Where does MDR TB occur?

The notified cases of MDR TB by World Health Organisation (WHO) region are given below.
Notified MDR TB by WHO Region 2011

Region Notified cases of multi drug resistant TB
Africa 12 384
Americas 2,969
Eastern Mediterranean 841
Europe 32 348
South-East Asia 6 615
Western Pacific 4 392
Global Total for multi drug resistant TB 59 549

Globally just under 60,000 cases of MDR TB were notified to WHO in 2011, mostly by European countries and South Africa. This represented just 19% of the 310,000 cases of MDR TB estimated to exist among the patients with pulmonary TB who were notified to WHO in 2011.The highest prevalence of MDR TB that had been documented by 2012 was in Minsk, Belarus, with a prevalence of 47.8% being reported in 2011. Among patients with infectious (smear positive) pulmonary disease, MDR TB was seen in 35.3% of newly detected cases, and in a massive 76.5% of previously treated patients.

Where does XDR TB occur?

By 2012 some 84 countries had reported at least one case of XDR TB. These are not just developing countries, but include countries such as England and the United States of America. The proportion of MDR TB cases with XDR TB was 9.0%.

High burden drug resistant TB countries

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. 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.

There is some more about TB in India as well as some more MDR TB statistics including the number of cases in each high burden country.WHO estimate that some 5% of people with MDR TB may actually have XDR TB. So if the actual number of MDR TB cases could be as high as 500,000 people, it means that as many as 25,000 cases of XDR TB could already have occurred.

The cost of treating drug resistant TB

The cost of just the drugs for treating the average multi drug resistant TB patient can be 50 to 200 times higher than the cost of treating a drug susceptible TB patient. The total costs though are much more than just the drug costs, and must include such costs as the equipment for diagnosis as well as all the labor costs

In addition although the disease may be the same in different countries of the world, the overall costs of treatment can be very different. This is not just because the finances and facilities may be different, but also because the expectations of both patients and health care workers and what is considered to constitute good treatment may be different.

Different countries, different expectationsFor example, in many countries discussion about the costs of drug resistant TB may well be about using DOTS Plus and whether it can be afforded, and can the system possibly afford drug susceptibility testing on all initial isolates of TB, as well as the cost of second line drugs for the treatment of drug resistant TB

A patient with drug resistant TB

A doctor checks for signs of life and finds none, in a patient with drug resistant TB in the Ukraine © Misha Friedman/WHO
By contrast, in many parts of the United States and in some parts of Western Europe, the political and social pressures regarding the financing of drug resistant TB control may well be to locate enough money for negative pressure isolation rooms, so that every single patient coming through the door of a hospital who might possibly have pulmonary TB, can be put in such a room and kept there until it has been proven that they have not got drug resistant TB.19
However, short term decisions about, for example, the affordability of drug susceptibility testing, can and indeed does result in a lack of effective treatment for drug resistant TB in many countries and areas. This not only causes many unnecessary deaths, but also helps to fuel the ongoing spread of drug resistant TB.

Treating drug resistant TB - the problems

There are a number of major problems with providing effective treatment for drug resistant TB. Although many of these also apply to the provision of treatment for drug susceptible TB, they are particularly important in respect of the large scale effective provision of treatment for drug resistant TB