A new blood test can now help doctors whether someone is likely to develop the active and fatal form of tuberculosis has become a realistic possibility.

Scientists have finally discovered a way which could tell the difference between the 10 percent of people infected with TB who will go on to develop the full-blown disease from the 90 percent of healthy carriers who have the latent form of the lung infection.

This new finding will now give a chance to the doctors to concentrate on treating the one in 10 infected people who are at high risk of becoming ill, rather than attempting to prescribe the potent anti-TB drugs to everyone who is shown to be infected with the bacterium.

Almost two million people worldwide die every year from TB, more so in the developing countries, but the disease has also returned in develop countries. 9,153 cases were recorded in 2009 in UK which is the largest annual rise since 2005, with nine out of 10 cases occurring in ethnic minorities.