Geneva: Tuberculosis claimed 1.3 million lives last year with drug-resistant forms of the infectious disease -- the deadliest after AIDS -- a huge global concern, the WHO warned on Wedesday.
Worldwide efforts to rein in the killer airborne disease helped drive the toll down 100,000 from the previous year, the World Health Organization said in its annual report on the fight against TB.
But the toll remains the world's second-highest for an infectious disease, after HIV/AIDS.
An estimated 8.6 million people caught tuberculosis in 2012, with India alone accounting for 26 percent of cases, and China, 12 percent.
According to the WHO, close to one-third of TB cases were in Southeast Asia, just over a quarter in Africa and around one-fifth on the Western Pacific region.
Looking at the longer-term picture, the number of infections fell by nearly half from 1990 to 2012.
But experts reckon only two-thirds of last year's 8.6 million new cases were actually diagnosed, leaving an estimated three million people unaware they had the disease.
Those most at risk are typically among the worst-off groups of the population, the report said.
"To find the three million TB cases means we need to reach beyond the current health services, we need to look at where these cases are," WHO expert Karin Meyer told reporters.
"These are often vulnerable populations, displaced populations, migrant population, quite difficult to reach," she added.
Global health experts also warned of the growing threat posed by a strain of TB that resists drugs used to fight the classic form.
Multidrug-resistant TB, or MDR-TB, which emerged due to erratic treatment of the regular strain or excessive use of anti-TB medication, claimed 170,000 lives last year, the WHO said.
Some 94,000 people were diagnosed with MDR-TB last year, twice the figure in 2011.
But the true number of cases is thought to be around five times higher, the WHO added.
'A real public health crisis'
The highest density of MDR-TB cases is found in the former communist countries of Eastern Europe and Central Asia.
In contrast, Africa has seen lower levels of MDR-TB, in part because of weaker access to standard TB treatment in the past.
Other countries hit hard by MDR-TB include China and India.
"The unmet demand for a full-scale and quality response to multidrug-resistant tuberculosis is a real public health crisis," said Mario Raviglione, head of the WHO's TB programme.
The standard drugs used to treat TB are isoniazid and rifampicin. Vaccines are in development, but are not expected to hit the market before 2025, the WHO said.
MDR-TB is able to ward off both isoniazid and rifampicin.
It can be treated with bedaquilin, which came onto the market at the end of last year and is the first new TB drug in four decades.
But bedaquilin is costly, the WHO stressed, with a $30,000 (22,000-euro) price tag for a six-month course of treatment in developed countries, and some $1,000 in the developing world.
Since the WHO launched a major anti-TB drive in 1995, a total of 56 million people have been treated and 22 million lives saved, the agency said.
"Quality TB care for millions worldwide has driven down TB deaths," said Raviglione.
"But far too many people are still missing out on such care and are suffering as a result. They are not diagnosed, or not treated, or information on the quality of care they receive is unknown," he added.
The agency also warned funding for its anti-TB campaign was falling short of its target.
A conventional two-year course of TB treatment costs between $4,000 and $10,000 in developing countries.
The WHO said it needed to bridge a $2 billion annual gap in order to meet its overall requirement of up to $8 billion a year to fight the disease in low and middle-income countries.