The battle against what used to be known as the White Death – tuberculosis – is apparently being won, with a steady year on year decline in the numbers infected with the disease and dying from it, according to the World Health Organisation.

The WHO's annual report says that 2010 saw the lowest number of cases and of deaths for a decade. There were 8.8 million cases of disease, down from 9 million in the peak year of 2005. Deaths dropped from 1.8 million in 2003 to 1.4 million.

Yet the UN warned that declining funding, as donor governments retrench in response to the tough economic climate, could put this progress at risk and cause problems in dealing with the worrying rise in cases of multi drug-resistant TB (MDRTB).

"Fewer people are dying of tuberculosis, and fewer are falling ill. This is major progress," said the UN secretary-general, Ban-ki Moon. "But it is no cause for complacency. Too many millions still develop TB each year, and too many die. I urge serious and sustained support for TB prevention and care, especially for the world's poorest and most vulnerable people".

Only 16% (46,000) of those with multi drug-resistant forms of the disease are being treated at the moment, which is alarming because without treatment, not only will the patient die but the disease is likely to be spread. Even ordinary TB requires a course of drugs lasting six months. MDRTB is even harder to treat because it requires years of antibiotics which are not commonly available and expensive. Of the $1bn said to be needed in 2012 to fund the fight against TB globally, $200,000 is for MDRTB.

A new rapid test is being rolled out, which is expected to revolutionise the diagnosis of MDRTB. "But the promise of testing more people must be matched with the commitment to treat all detected. It would be a scandal to leave diagnosed patients without treatment," said Dr Mario Raviglione, director of WHO's Stop TB department.

The best progress has been made in big countries with large numbers of people affected by TB, which is a significant killer in people with HIV. Among them are Kenya and Tanzania. Brazil has also reported a steady decline in cases and China has made dramatic progress. Overall, the death rate dropped by 40% between 1990 and 2010. If this continues, all regions except Africa are on track to cut mortality by 15% by 2015.

In 2009, 87% of patients treated were cured, with 46 million people successfully treated and 7 million lives saved since 1995. However, a third of estimated TB cases worldwide are not notified and therefore it is unknown whether they have been diagnosed and properly treated.