ScienceDaily (Dec. 16, 2008) — Levels of drug-resistant tuberculosis (TB) in China are nearly twice the global average. Nationwide research published in the journal BMC Infectious Diseases has shown that almost 10% of Chinese TB cases are resistant to the most effective first-line drugs.

Susan van den Hof, from the KNCV Tuberculosis Foundation in The Netherlands is one of the authors on a Chinese study into the prevalence of multi-drug resistant tuberculosis (MDR-TB). She said, "In order to obtain insight into the prevalence and distribution of resistance, China has joined the global project on anti-tuberculosis drug resistance surveillance, and investigated drug resistance in ten provinces between 1996 and 2004."

China has the second largest number of TB cases in the world, and is one of the countries with high levels of drug-resistant TB. According to the authors, "The prevalence of drug resistance varied greatly between the provinces, but on average was worryingly high, with a weighted mean for MDR-TB of 9.3% among all cases; 5.4% among new cases and 25.6% among previously treated cases. The global MDR-TB estimates are 4.8% for all cases, 3.1% for new cases and 19.3% for previously treated cases."

Treatment of MDR-TB requires use of costly, toxic and less effective second-line drugs and infected patients are less likely to survive treatment. In a well-functioning TB control program with low levels of defaulting from treatment, high resistance levels are expected among previously treated cases. This is consistent with the authors' observations in China. If a good TB control program is in place, the proportion of previously treated patients among all TB patients should also be low. In China the proportion of previously treated patients varied between the provinces but on average was about 20%, compared to a global average of 11%.

The authors said, "Many possible explanations for the development of drug resistance in China exist, and different explanations may prevail in different areas of this vast country. These include the inadequate use of anti-TB drugs in public hospitals, lack of supervision of treatment, poor drug-management and absence of infection control measures in hospitals. Also, availability of anti-TB drugs without a prescription in some areas of China in the past may have contributed to the development of drug resistance."

At this moment, programmatic treatment of MDR-TB cases with second-line drugs is being piloted in some areas of China. MDR-TB treatment will then be expanded within China to prevent further spread of MDR-TB and help to bring MDR-TB rates down.

Journal Reference:

1. Guang Xue He, Yan Lin Zhao, Guang Lu Jiang, Yu Hong Liu, Hui Xia, Sheng Fen Wang, Li Xia Wang, Martien W Borgdorff, Marieke J van der Werf and Susan van den Hof. Prevalence of tuberculosis drug resistance in 10 provinces of China. BMC Infectious Diseases, (in press)

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