The World Health Organization conducted a survey in 79 countries under the Global Project on Anti-Tuberculosis Drug Resistance Surveillance, which was set up in 1994, and found high levels of Multidrug-resistant TB strains worldwide. These were more prevalent in certain parts of former Soviet Union and parts of China and India.
About one third of the world's population is supposed to be infected with the TB bacterium and around 8.9 million develop TB every year.
In 2004, this dangerous respiratory disease caused 1.7 million deaths worldwide.
Anti-microbial drugs are often used for treating TB and have proved very effective, but it is believed their misuse has made the bacteria more resistant and resulted in newer strains that are drug-resistant.
Patients often fail to complete a full course of the drugs and small amounts of the bacteria that may remain, returns with more vigour and resistance.
Multidrug-resistant TB strains are found to be resistant to the two most potent drugs, isoniazid and rifampicin.
Scientists have recently reported an even more extensive drug-resistant TB strain,which has been found among people with HIV in South Africa.
'MDR-TB is a precursor to XDR-TB [extensive drug-resistant tuberculosis], recently reported among HIV-infected people in South Africa,' wrote study author Mario Raviglione.
He said the study findings 'emphasize the importance of implementing sound tuberculosis control activities to prevent further creation of MDR tuberculosis and the necessity of mainstreaming high-quality treatment for MDR tuberculosis into routine tuberculosis control programs. Otherwise, XDR-TB is bound to keep emerging as a fatal variant of TB, especially in high HIV-prevalence settings.'