The number of people in the world newly infected with tuberculosis fell again last year, dropping by 2.2 percent, but the burden of TB looms large and the pace of diagnosis of drug-resistant strains of the infection is slow, the World Health Organization said on Wednesday.

In its annual assessment, WHO cited progress toward global targets for reducing tuberculosis cases and deaths, noting that the United Nation's Millennium Development Goal target to halt and reverse the epidemic by 2015 has been achieved.

"In the space of 17 years, 51 million people have been successfully treated and cared for according to WHO recommendations. Without that treatment, 20 million people would have died," Dr. Mario Raviglione, director of the WHO Stop TB Department, said in a statement.

The report features data from 204 countries and territories, and includes all aspects of TB, including resistant forms, rates of TB and HIV co-infections, research and development and financing.

Overall, it found that 8.7 million people fell ill with tuberculosis in 2011 and 1.4 million died, including nearly 430,000 people who were also infected with HIV, the virus that causes AIDS.

Not all countries enjoyed equal progress in curbing the disease.

Cambodia, for example, has made significant strides in reducing TB rates, with the number of cases dropping by 45 percent between 2002 and 2011. But the African and European regions are not on track to halve 1990 levels of mortality by 2015.

According to the report, progress has been slow in identifying cases of drug-resistant tuberculosis, estimating that only 1 in five patients who are thought to be infected with difficult-to-treat cases of TB are being diagnosed worldwide.

And WHO officials worry about funding cuts that could stall progress in fighting the disease.

"The momentum to break this disease is in real danger. We are now at a crossroads between TB elimination within our lifetime, and millions more TB deaths," Raviglione said in a statement.