People in China and former Soviet states are being hit hard by potentially dangerous strains of tuberculosis, researchers said Thursday.

In the medical journal The Lancet, experts from the World Health Organization said 19 per cent of tuberculosis infections are multi-drug resistant or MDR-TB, and rates were particularly high in Azerbaijan, Moldova, Estonia and Latvia.

In wealthier countries on the other hand, only one per cent of infections could not be treated with two or more main TB drugs.

"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 researchers wrote.

The prevalence of MDR-TB in two Chinese provinces was seven per cent, compared with between seven per cent and 22 per cent in nine countries of the former Soviet Union.

Regionally, Eastern Europe had the highest prevalence at 19 per cent, followed by Southeast Asia at four per cent, Latin America with three per cent and Africa at two per cent, Dr. Abigail Wright and Dr. Dennis Falzon of WHO in Switzerland and their colleagues said.

"[T]he problem of XDR tuberculosis is likely to increase and without appropriate laboratory capacity or new drugs, the world is ill-equipped to manage this emerging crisis," the team concluded. (XDR is extensively drug-resistant tuberculosis, which WHO calls "virtually untreatable.")

In an accompanying commentary, Dr. Martien Borgdorff, of the University of Amsterdam, Netherlands, and Dr. Peter Small of the Bill and Melinda Gates Foundation, discussed some promising developments, such as rapid diagnostic tests, new types of TB drugs, and early signs of action in countries like India and South Africa.

About 490,000 of the 9 million new cases of tuberculosis worldwide each year are multidrug-resistant, according to WHO.