As many as 32,000 children worldwide become sick each year with a drug-resistant "superbug" strain of tuberculosis, according to new estimates by US researchers that for the first time quantify rates of this difficult-to-treat form of TB.

Overall, as many as 1 million children become sick with TB each year, about twice the number previously thought, and of these, only a third of the cases are ever diagnosed, the study found. "

A huge proportion (of children) are suffering and dying from TB unnecessarily," says Helen Jenkins of Brigham and Women's Hospital's Division of Global Health Equity, the lead statistician on the study published on Sunday in the Lancet.