According to reports, tuberculosis cases are falling dramatically in the United States, but drug-resistant strains of the disease are rising in other areas of the world.

The Los Angeles Times reported on Sunday that the U. S. Centers for Disease Control and Prevention reported U. S. cases of the disease fell by 11.8 percent in 2009, the largest yearly drop since monitoring began in 1953.

The newspaper said that according to an estimate of the World Health Organization, 440,000 people contracted multi-drug-resistant tuberculosis in 2008, and a third of them died.

WHO also said that about half of those cases were in China and India, the countries which are hardest hit in the outbreak. But in some parts of the world, 25 percent of cases are from the drug-resistant strains.

The Times further said that experts worry the hard-to-treat strains will overtake conventional strains of the TB mycobacterium, complicating treatment. Drugs to treat conventional TB cost about $20, and treatment takes six months. Drug-resistant strains can push the cost to as much as $500, and effective treatment can take up to two years. (With Inputs from Agencies)