Multi-drug resistant tuberculosis (MDR-TB) has reached "epidemic" levels in many ex-Soviet nations, and is widespread in several provinces of China, according a new global assessment.
Data on more than 90,000 patients in 83 countries covering the period 2002-2007 showed that one-in-nine of the approximately nine million new cases of tuberculosis each year failed to respond to at least one anti-TB drug.
The rates of MDR-TB -- defined as resistant to at least two frontline medications -- were between seven and 22 percent in nine countries from the former Soviet Union, including 19 percent in Moldova and 22 percent in Baku, Azerbaijan.
Overall, nearly a fifth of all TB cases in Eastern Europe were drug resistant.
"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 study concluded.
In most rich nations, including France, Britain, the Netherlands and New Zealand, the prevalence of drug resistant TB was one percent or lower.
All told, more than half-a-million cases of MDR-TB have emerged since 2006, according to the study, published in the British medical journal The Lancet. Half of them were in China and India.
The most common types of TB can be easily cured with ten euros (14 dollars) worth of medicine if diagnosed early.
But new strains that have built up immunity to standard antibiotics -- especially isoniazid and rifampicin -- can require drug treatments costing thousands of dollars (euros) and lasting a year to 18 months.
And even when properly treated, MDR-TB patients still face a significantly increased risk of death.
The study also found that virulent strain infection rates had increased in many countries since the mid-1990s, when the Global Project on Anti-Tuberculosis Drug Resistance was launched.
Between 1994 and 2007, prevalence jumped from 1.6 to 2.7 percent of all TB cases in South Korea. The percentage of MDR-TB more than doubled in six years -- from 6.5 to 15 percent -- in the Tomsk Oblast region of Russia, and nearly quadrupled between 2002 and 2006 to 8.8 percent in Orel Oblast, also in Russia.
Rates in the Baltic nations of Estonia and Latvia held steady over the course of a decade at 11.3 percent and 10.8 percent, and declined over the same period in Hong Kong and the United States to about one percent.
An even more deadly and virtually untreatable form of the disease, called extensively drug-resistant (XDR) tuberculosis, showed up in 37 nations, with more than 25 cases reported in five former Soviet states: Azerbaijan, Estonia, Latvia, Lithuania and Russian Federation (Tomsk).
"Currently, the world is far behind reaching targets for MDR-TB diagnosis and management," the study warned.
The World Health Organisation (WHO) said last month that progress in tackling tuberculosis was far too slow, doubling its estimate of the ravages the disease is causing among HIV/AIDS patients.
Some 9.27 million people contracted TB in 2007, an increase of about 30,000 over the previous year mainly in line with population growth.
They included some 1.4 million people with HIV/AIDS, compared to an estimated 600,000 in 2006.
More than one death in four -- 456,000 of the 1.75 million tuberculosis deaths recorded in 2007 -- is now thought to involve an HIV/AIDS patient.