Anti-tuberculosis drug resistance in the world

Feb 27 2008

Multidrug-resistant tuberculosis (MDR-TB) has been recorded at the highest rates ever, according to a new report.

The report presents findings from the largest survey to date on the scale of drug resistance in tuberculosis.

The report, "Anti-tuberculosis drug resistance in the world" , is based on data collected between 2002 and 2006 on 90 000 TB patients in 81 countries. It found that extensively drug-resistant tuberculosis (XDR-TB), a virtually untreatable form of the respiratory disease, has been recorded in 45 countries.

The report also found a link between HIV infection and MDR-TB. Surveys in Latvia and Ukraine found nearly twice the level of MDR-TB among TB patients living with HIV compared with patients without HIV.

Based on the analysis of the survey data, WHO estimates there are nearly half a million new cases of MDR-TB a year, which is about 5% of nine million new TB cases of all types. The highest rate was recorded in Baku, the capital of Azerbaijan, where nearly a quarter of all new TB cases (22.3%) were reported as multidrug-resistant.

Proportions of MDR-TB among new TB cases were 19.4% in Moldova, 16% in Donetsk in Ukraine, 15% in Tomsk Oblast in the Russian Federation, and 14.8% in Tashkent in Uzbekistan. These rates surpass the highest levels of drug resistance published in the last WHO report in 2004. Surveys in China also suggest that MDR-TB is widespread there.

Frontal assault needed

"TB drug resistance needs a frontal assault. If countries and the international community fail to address it aggressively now we will lose this battle," said Dr Mario Raviglione, Director of the WHO Stop TB Department. "In addition to specifically confronting drug-resistant TB and saving lives, programmes worldwide must immediately improve their performance in diagnosing all TB cases rapidly and treating them until cured, which is the best way to prevent the development of drug resistance."

For the first time, the global survey includes analysis of XDR-TB. However, because few countries are currently equipped to diagnose it, limited data were available for this report.

The report also points to some successes. Thirteen years ago, Estonia and Latvia were singled out by WHO as drug-resistant TB "hotspots". Following a substantial investment and a sustained assault on MDR-TB, rates in these two Baltic countries are today stabilizing and TB case notification rates are falling.

The true scale of the problem also remains unknown in some pockets of the world. Only six countries in Africa - the region with the highest incidence of TB in the world - were able to provide drug resistance data. Other countries in the region could not conduct surveys because they lack the equipment and trained personnel needed to identify drug-resistant TB. "Without these data, it is difficult to estimate the true burden and trends of MDR-TB and XDR-TB in the region. It is likely there are outbreaks of drug resistance going unnoticed and undetected," said WHO TB expert Abigail Wright, the principal author of the report.

WHO estimates that US$ 4.8 billion is needed for overall TB control in low- and middle-income countries in 2008, with US$ 1 billion for MDR-TB and XDR-TB. But there is a total finance gap of US$ 2.5 billion, including a US$ 500 million gap for MDR-TB and XDR-TB.

"The threat created by TB drug resistance demands that we fill these gaps, as laid out in the Global Plan to Stop TB, a roadmap for halving TB prevalence and deaths compared with 1990 levels by 2015," said Dr Marcos Espinal, Executive Secretary of the Stop TB Partnership. "The Plan also calls for another imperative - sufficient resources for research to find new diagnostics, new drugs effective against resistant strains and an effective TB vaccine."