Mycobacterium tuberculosis, the TB-causing bacteria

NIAID

[BEIJING] China has one of the highest levels of multi-drug resistant tuberculosis (MDR-TB) in the world, a survey has found.

The proportion of TB sufferers in China who have the multi-drug resistant variety is double the global average, according to a survey of over 14,000 sufferers in 10 provinces published in the open access journal BMC Infectious Diseases earlier this month (11 December).

The study, conducted by Chinese and Dutch researchers, shows that the prevalence was 9.3 per cent compared with global estimates of 4.8 per cent. The authors say the figures are "worryingly high".

Patients with MDR-TB have to be treated with costly, toxic and less effective drugs — and infected patients are less likely to survive treatment.

"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," are all possible factors, the authors wrote in their paper.

The highest resistance rates were found in Henan, Liaoning, Inner Mongolia and Heilongjiang provinces. The latter two border the Russian Federation, where resistance levels are known to be extremely high. Liaoning borders these two provinces, suggesting that prevalence may relate to regional factors.

Zheng Suhua, an epidemiologist at the Beijing Tuberculosis Institute, agrees with the conclusions.

"It hasn't been proved yet, but prevalence of drug resistant TB is probably affected by regional factors. Different strains make different types of drug resistant TB."

But in the case of Henan, the prevalence of MDR-TB in two neighbouring provinces is low. As well as population and economic factors, the rate is also closely related to the prevalence of HIV/AIDS there.

"AIDS patients are very easily infected by TB, and about one third of them die from it," Zheng told SciDev.Net.

Comparing different provincial rates is of limited use, however, because the data span eight years, said co-author Zhao Yanlin from the National Tuberculosis Reference Laboratory in the Chinese Centre for Disease Control and Prevention.

China is currently conducting its first nationwide survey of drug-resistant TB and the data will emerge in the first half of 2009.

Link to full article/paper in BMC Infectious Disease