Drug-resistant tuberculosis burden much higher in former Soviet states and China

The fourth round of data from the Global Project on Anti-Tuberculosis Drug Resistance shows the majority of the multi-drug resistant (MDR) tuberculosis (TB) burden falls in China and former Soviet states — where it is far higher than in high-income countries. The findings are reported in an Article published Online First and in an upcoming edition of The Lancet, written by Dr Abigail Wright and Dr Dennis Falzon, WHO, Switzerland, and colleagues.

The researchers gathered data from over 90,000 patients in 83 countries and territories between 2002 and 2007. Standardised collection of results allowed comparison between and within countries. Data for HIV status and cases of extensively-drug resistant (XDR) TB were also collected where possible.

They found that for new cases of TB, the median prevalence of resistance to any drug was 11% (or one in nine cases). The prevalence of MDR-TB ranged from 0% in eight countries (mostly very small nations) to 7% in two provinces in China, and between 7% and 22% in nine countries of the former Soviet Union, including 19% in Moldova and 22% in Baku, Azerbaijan*. In high-income countries, the prevalence of MDR-TB among new TB cases was much lower (France 1%, Germany 2%, UK, Netherlands, New Zealand all <1%).

Trend analysis showed that, between 1994 and 2007, the prevalence of MDR in new TB cases increased substantially in South Korea (1.6% in 1994 to 2.7% in 2004) and in Tomsk Oblast (6.5% in 1999 to 15.0% in 2005) and Orel Oblast (2.6% in 2002 to 8.8% in 2006), Russia, but was stable in Estonia and Latvia (13.3% and 10.8% respectively in 2005). The prevalence of MDR-TB in all TB cases decreased in Hong Kong (2.6% in 1996 to 0.9% in 2005) and the USA (2.4% in 1994 to 1.2% in 2005). Looking at the data on a regional and income basis, in high-income countries prevalence of MDR among all TB cases was 1%. Eastern Europe had the highest prevalence (19%), Latin America 3%, Africa 2%, and Southeast Asia 4%. XDR-TB cases were reported by 37 countries having representative surveillance data. Five former Soviet states (Azerbaijan [Baku], Estonia, Latvia, Lithuania, and Russian Federation [Tomsk]) each reported 25 cases or more, with prevalence of XDR-TB among the total of MDR-TB cases ranging from 7 to 24% in these countries.

The authors say: "Data from our global survey show regional and national variation in the magnitude and trends in drug-resistant TB. Countries of the former Soviet Union, followed by some provinces of China, reported the highest prevalence of resistance, while the eastern Mediterranean region and southeast Asia reported prevalence of resistance on par with estimated global averages. The data presented here show that of the half a million MDR-TB cases estimated to have emerged in 2006, 50% were in India and China alone, and 27 countries account for 86% of the world's MDR-TB burden. Countries in the Americas, western and central Europe, and Africa reported the lowest prevalences of MDR-TB." They add: "The countries of the former Soviet Union are facing a serious and widespread epidemic with the highest prevalence of MDR-TB ever reported in 13 years of global data collection."

The authors conclude by discussing the importance of countries fully implementing the new Stop TB Strategy, which was launched in 2006 and expands upon the directly observed short-course treatment (DOTS) approach. They say: "Currently, the world is far behind reaching the targets for MDR-tuberculosis diagnosis and management set out in the second Global Plan to Stop TB 2006�. Until drug susceptibility testing is implemented routinely for tuberculosis cases as the standard for diagnosis and surveillance, survey mechanisms will continue to be crucial for the determination of trends and the documentation of emergence of further resistance to second-line drugs."

In an accompanying Comment, Dr Martien W Borgdorff, Academic Medical Centre, University of Amsterdam, Netherlands, and Dr Peter M Small, Bill and Melinda Gates Foundation, USA, and Institute for Systems Biology, USA, discuss some promising developments regarding rapid diagnostic tests and TB drugs with new mechanisms of action.

They conclude: "Worldwide, there are early signs of action. A group of countries, which together have nearly 45% of the world's TB and high rates of drug resistance, are leading new control efforts. In March, Brazil hosted the Stop TB Partners' Forum in Rio de Janeiro, and China convened a meeting of countries most affected by MDR-TB. India has set an objective for universal access to MDR-TB treatment and South Africa is now home to crucial clinical research trials of vaccines, drugs and diagnostics. These commitments could herald a new framework in global health in which endemic countries with emerging economies stimulate a global response."

Dr Dennis Falzon, WHO, Switzerland T) +41 22791146 E) falzond@who.int (Dr Wright is currently on leave)

Dr Martien W Borgdorff, Academic Medical Centre, University of Amsterdam, Netherlands T) +31 20 566 2349 E) m.w.borgdorff@amc.uva.nl

Dr Peter Small, Bill and Melinda Gates Foundation, USA T) +1 206 709 3400 E) media@gatesfoundation.org

For full Article and Comment, see: http://press.thelancet.com/worldmdrtb.pdf and for a web appendix with supplementary data, see: http://press.thelancet.com/worldmdrtbappendix.pdf

Notes to editors: *For some countries, data was provided for whole countries, while for others it was provided for certain cities or regions. See full paper/appendix.