WHO Finds Global Drug-Resistant TB at Record Levels

By Peggy Peck
GENEVA, Feb. 27 -- Cases of multidrug-resistant tuberculosis have reached record levels worldwide and extensively drug-resistant tuberculosis (XDR-TB) has spread to 45 countries, according to the World Health Organization.
In its first major TB report in four years, the WHO estimated the global proportion of drug-resistant TB at 4.6%. China and India are estimated to account for 50% of the global burden of drug-resistant cases with the Russian Federation adding a further 7%.
The WHO findings were derived from data collected from 2002 through 2006 on 90,000 TB patients in 81 countries.
These survey data mark the first time that the global analysis included information about XDR-TB, but because few countries are currently equipped to diagnose this emerging disease, limited data were available for the report.
On the basis of the survey data, the WHO estimates there are nearly half a million new cases of MDR-TB a year, or about 5% of the 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 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 previous WHO report in 2004. Surveys in China also suggest that MDR-TB is widespread there.
But the true scale of the problem is unknown because few countries at risk have the needed surveillance programs, said Abigail Wright, M.P.H., a WHO TB expert who was the lead author of the report.
For example, only six countries in Africa -- the region with the highest occurrence rate 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," Wright said. "It is likely there are outbreaks of drug resistance going unnoticed and undetected."
The WHO also identified a link between HIV infection and MDR-TB in Latvia and Ukraine, where HIV-infected TB patients were twice as likely to have MDR-TB as patients who were not HIV-positive.
According to WHO, effective control of TB in low and middle-income countries would cost $4.8-billion in 2008, with $1-billion of that earmarked for MDR-TB and XDR-TB control. But the said current funding for TB control is $2.5-billion short of the needed amount.
Mario Raviglione, M.D., director of the WHO Stop TB Department, said fighting the growth of resistant TB strains requires "a frontal assault. If countries and the international community fail to address it aggressively now, we will lose this battle."