XDR-TB

[Guest guest]

All, FYI.

Especially those working in Africa.

Regards

J

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http://www.who.int/mediacentre/news/notes/2006/np23/en/index.html

Emergence of XDR-TB

WHO concern over extensive drug resistant TB strains that are virtually

untreatable

5 SEPTEMBER 2006 | GENEVA -- The World Health Organization (WHO) has

expressed concern over the emergence of virulent drug-resistant strains of

tuberculosis (TB) and is calling for measures to be strengthened and

implemented to prevent the global spread of the deadly TB strains. This

follows research showing the extent of XDR-TB, a newly identified TB threat

which leaves patients (including many people living with HIV) virtually

untreatable using currently available anti-TB drugs.

What is XDR-TB?

MDR-TB (Multidrug Resistant TB) describes strains of tuberculosis that are

resistant to at least the two main first-line TB drugs - isoniazid and

rifampicin. XDR-TB, or Extensive Drug Resistant TB (also referred to as

Extreme Drug Resistance) is MDR-TB that is also resistant to three or more

of the six classes of second-line drugs.

The description of XDR-TB was first used earlier in 2006, following a joint

survey by WHO and the US Centers for Disease Control and Prevention (CDC).

Resistance to anti-TB drugs in populations is a phenomenon that occurs

primarily due to poorly managed TB care. Problems include incorrect drug

prescribing practices by providers, poor quality drugs or erratic supply of

drugs, and also patient non-adherence.

What is the current evidence of XDR-TB?

Recent findings from a survey conducted by WHO and CDC on data from

2000-2004 found that XDR-TB has been identified in all regions of the world

but is most frequent in the countries of the former Soviet Union and in

Asia.

In the United States, 4% of MDR-TB cases met the criteria for XDR-TB.

In Latvia, a country with one of the highest rates of MDR-TB, 19% of MDR-TB

cases met the XDR-TB criteria.

Separate data on a recent outbreak of XDR-TB in an HIV-positive population

in Kwazulu-Natal in South Africa was characterized by alarmingly high

mortality rates.

Of the 544 patients studied, 221 had MDR-TB. Of the 221 MDR-TB cases, 53

were defined as XDR-TB. Of the 53 patients, 44 had been tested for HIV and

all were HIV-positive.

52 of 53 patients died, on average, within 25 days including those

benefiting from antiretroviral drugs.

Scarce drug resistance data available from Africa indicate that while

population prevalence of drug resistant TB appears to be low compared to

Eastern Europe and Asia, drug resistance in the region is on the rise.

Given the underlying HIV epidemic, drug-resistant TB could have a severe

impact on mortality in Africa and requires urgent preventative action.

What action is required to prevent XDR-TB?

XDR-TB poses a grave public health threat, especially in populations with

high rates of HIV and where there are few health care resources.

Recommendations outlined in the WHO Guidelines for the Programmatic

Management of Drug Resistant Tuberculosis include:

- strengthen basic TB care to prevent the emergence of drug-resistance

- ensure prompt diagnosis and treatment of drug resistant cases to

cure existing cases and prevent further transmission

- increase collaboration between HIV and TB control programmes to

provide necessary prevention and care to co-infected patients

- increase investment in laboratory infrastructures to enable better

detection and management of resistant cases.