The World Health Organization has been concerned about the development of drug- resistant strains of TB for several years. The strains have developed because patients discontinue treatment or don't follow treatment courses correctly, or because they have been prescribed poor quality drugs.

WHO's new report on the spread of multi-drug resistant TB (MDR-TB) reveals that in some parts of the world, one in four TB patients now have the multi-drug resistant strain.

“We estimate there are now half a million cases of MDR-TB every year,“ said Dr. Matteo Zignal, co-author of the report. “In this report we have documented the highest rates of drug resistant TB ever recorded.”

“This is in the north-west of Russia, where one out of four patients presenting with TB have this more serious form of the disease,” Zignal said.

Hard to treat

Multi-drug resistant TB is, as its name suggests, very hard to treat, since it does not respond to traditional TB medicines.

Instead patients are required to take a cocktail of far more expensive drugs over a longer period. What's more, these drugs tend to have serious side effects.

Little wonder then that world wide, just seven per cent of patients with MDR-TB are receiving the treatment they need.

“Put yourself in the position of a severely ill person, unemployed, and stigmatised, having to take drugs for two years,” said TB specialist Ernesto Jaramillo.

“It's very difficult to keep adhering to the treatment.”

Fatal consequences

But giving up on treatment for MDR-TB can have fatal consequences: the rise of extreme drug resistant tuberculosis, or XDR-TB. This strain is virtually untreatable, and even with the best possible care, the survival rate is less than 60 per cent.

WHO's new report shows that 58 countries have now reported cases of XDR-TB, but this may just be the tip of the iceberg.

Across the continent of Africa, just two laboratories - one in Algeria and one in South Africa - have the capacity to even identify the XDR-TB strain.

“It's urgent to invest more in…new diagnostics that can enable access to timely detection of the disease and prompt treatment,” said Jaramillo.

Drug resistant strains spreading

A further worry for WHO is that carriers of drug resistant TB strains spread the drug resistant variety to those they come in contact with, and not, as some patients believe, the original, more easily treatable strain.

What it all adds up to is not just a major health crisis, but a big threat to all the work done in the last decades to eradicate TB.

“There has been a lot of progress in controlling TB,” said Ernesto Jaramillo. “And now this progress is threatened seriously by MDR-TB.”

“And the evidence in our report shows that in countries where there is no action in continuing to try to control TB, you find a high proportion of MDR-TB,” Jaramillo said.

WHO will present its full report on all strains of tuberculosis worldwide later this year.

But it's already clear, TB experts say, that rapid diagnosis and treatment for the drug resistant strains is now a matter of extreme urgency.

Author: Imogen Foulkes

Editor: Susan Houlton