The global tuberculosis (TB) epidemic is set to decline but progress is being hampered by HIV/AIDS and the emergence of extensively drug-resistant TB, according to a new report by the World Health Organization.

The report, released today (22 March) found that the global incidence rate of TB levelled off at 150 cases per 100,000 people in 2005.

"We are currently seeing the fruits of global action to control TB," said UN secretary-general Ban Ki-moon in a press statement.

Although the global incidence rate has stabilised, the actual number of TB cases — nearly nine million — has continued to rise slowly due to the expanding world population and the threat posed by HIV/AIDS.

HIV is the main reason for failure to meet TB control targets, particularly in sub-Saharan Africa.

The report recommends screening HIV patients to improve the detection of TB, and increasing collaboration between TB and HIV programmes (see Power struggles and the fight against TB and HIV), which it says is key to reducing the burden of TB among people living with HIV.

It also cites uneven access to diagnosis and treatment, and weak infrastructure and health systems in developing countries as further impediments to rapid progress against TB.

And although funds for TB control have risen substantially since 2002 ― reaching US$2 billion ― the report says an additional US$1.1 billion will be needed to achieve the 2007 targets set by the Global Plan to Stop TB.

The report says extensively drug-resistant TB (XDR-TB), which is resistant to three or more of the six classes of second-line drugs, poses a serious threat to progress and could even reverse recent gains.

"We have a clear plan on how to control XDR-TB but countries are moving far too slowly on implementing this plan," says Mario Raviglione, director of the World Health Organization's Stop TB Department.

He said the threat of XDR-TB has made research to identify new diagnostics, drugs and vaccines more vital than ever.

An extra US$650 million is needed this year to implement control measures for both XDR-TB and multi-drug-resistant TB, says Raviglione.

A survey conducted by the World Health Organization in 2004 found that XDR-TB has been identified in all regions of the world but is most frequent in the countries of the former Soviet Union and Asia, and most recently South Africa (see 'Virtually untreatable' TB hits South Africa).