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Drug-resistant Tuberculosis

7. Conclusions

  • 7.1 Magnitude and trends of drug-resistant tuberculosis
  • 7.2 Extensively drug-resistant tuberculosis (XDR-TB)
  • 7.3 Drug-resistant tuberculosis and HIV
  • 7.4 Survey coverage and methods
  • 7.5 Tuberculosis control and drug-resistant tuberculosis

7.1 Magnitude and trends of drug-resistant tuberculosis

Patients need to be registered into a suitable treatment programme.
Patients need to be registered into a suitable treatment programme.
Source: Gary Hampton

In 2006, approximately half a million new cases of multidrug resistant tuberculosis (MDR-TB) emerged in the world. China and India are estimated to carry 50% of the global burden of cases, and the Russian Federation is estimated to carry a further 7%.

Globally, MDR-TB makes up 4.6% of all cases of tuberculosis but, in some parts of the former Soviet Union, this proportion exceeds 35%. The patients in these countries have forms of tuberculosis that are resistant to a wide range of drugs, with the highest rates of extensively drug resistant tuberculosis (XDR-TB) in the world.

China has the second highest proportion of MDR-TB among TB cases but, in absolute terms, it has the highest number of MDR-TB cases in the world. The high proportion of drug-resistant TB among new cases in China suggests a concerning level of transmission of drug-resistant forms of TB.

In most countries where cases of TB are relatively few, the absolute numbers of cases of drug-resistant tuberculosis as well as the proportions of resistance are stable. Trend results are good in Hong Kong where MDR-TB is falling faster than tuberculosis. In Peru and in South Korea, tuberculosis is declining but MDR-TB is increasing. In Peru this could be due to a weakening in the control of the disease but in South Korea it may be due to changes in the surveillance method and not reflect a true worsening of the situation.

In the Baltic countries, tuberculosis is declining and levels of MDR-TB are relatively stable. However, in parts of the Russian Federation drug-resistance is rising rapidly, both in absolute numbers and in terms of proportion among new TB cases. Tuberculosis control is improving but there is a large pool of long-term cases that continues to fuel the epidemic. Current efforts to control the disease will have to be accelerated to have any impact in what appears to be a growing epidemic of drug-resistant tuberculosis.

This text is a summary of: WHO,  Anti-Tuberculosis Drug Resistance in the World, Fourth Global Report (2008), Executive Summary: Conclusions, Magnitude of drug resistant TB &Trends (p.16-18)

7.2 Extensively drug-resistant tuberculosis (XDR-TB)

Extensively drug-resistant tuberculosis (XDR-TB) can only be treated with a handful of drugs and these are more expensive and have worse side-effects than those used to treat multidrug-resistant tuberculosis (MDR-TB).

Extensively drug-resistant tuberculosis is widespread and 45 countries have reported at least one case. There is a significant problem within countries of the former Soviet Union, where cases of XDR-TB are high both in absolute and in relative terms. Levels of resistance to second-line drugs are also high in Japan and South Korea, and moderate in South Africa.

Elsewhere, in Africa, levels of extensively drug-resistant tuberculosis seem to be low. XDR-TB is likely to emerge as a result of inappropriate use of second-line anti-tuberculosis drugs, but these drugs are not yet widely used in the region

In order to understand the extent and the pattern of extensively drug-resistant tuberculosis throughout the world, all countries need to increase their efforts to measure resistance to second-line anti-tuberculosis drugs.

This text is a summary of: WHO,  Anti-Tuberculosis Drug Resistance in the World, Fourth Global Report (2008), Executive Summary: Conclusions, XDR-TB (p.18)

7.3 Drug-resistant tuberculosis and HIV

There is a significant association between HIV and multidrug-resistant tuberculosis (MDR-TB). A major reason for this association might be environmental: people become infected with both HIV and MDR-TB in places where patients are in close contact with each other such as health care facilities and prisons. Improving infection control in these settings may be critical to reducing the number of people infected with both HIV and multidrug-resistant tuberculosis.

People who have both infections at the same time are likely to die from TB unless they are diagnosed and treated quickly. This is a great concern for countries without sufficient testing facilities.

It is extremely important to develop methods that can detect drug-resistant tuberculosis quickly, particularly for HIV infected patients.

This text is a summary of: WHO,  Anti-Tuberculosis Drug Resistance in the World, Fourth Global Report (2008), Executive Summary: Conclusions, MDR and HIV (p.19)

7.4 Survey coverage and methods

Monitoring of drug resistance should be part of routine surveillance, but this requires culture and drug susceptibility testing to be the standard of diagnosis. Since many countries do not yet have these facilities, surveys are important to determine the extent of the drug resistance problem. Survey coverage and reliability of data are increasing, but major gaps remain. For instance, it is very difficult to determine trends in most high burden countries.

The largest obstacle is the lack of laboratory capacity. Testing for resistance to second-line drugs is not available in most countries and it has been difficult to introduce HIV testing as part of the general care for tuberculosis. Supranational reference laboratories will continue to provide testing for resistance while countries develop their own national facilities.

New methods to detect and monitor drug-resistant tuberculosis are being developed. Special studies are necessary to answer questions such as the risk factors for acquiring drug-resistant tuberculosis, or how the disease is transmitted in different populations.

This text is a summary of: WHO,  Anti-Tuberculosis Drug Resistance in the World, Fourth Global Report (2008), Executive Summary: Conclusions, Coverage and methods (p.19-20)

7.5 Tuberculosis control and drug-resistant tuberculosis

The main priority for all countries is to prevent the development of drug resistant tuberculosis but all cases that emerge have to be treated properly.

Some countries need to develop ways of detecting and treating drug-resistant cases quickly. This is particularly important in countries with high proportions of anti-tuberculosis drug resistance, countries with high absolute numbers of multidrug-resistant tuberculosis (MDR-TB), and countries with a TB population heavily co-infected with HIV.

New drugs to treat multidrug-resistant tuberculosis are urgently needed.

To control MDR-TB there needs to be a coordinated effort from all countries. The three priority areas include improvements in infection control measures to prevent transmission, expansion of testing services to detect cases quickly, and community involvement to ensure patients get tested and take all their drugs regularly. Most importantly, all patients must be registered in a suitable treatment programme.

This text is a summary of: WHO,  Anti-Tuberculosis Drug Resistance in the World, Fourth Global Report (2008), Executive Summary: Conclusions, TB Control and drug resistant TB (p.20)


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