/ 18 December 2006

Drug resistant TB cases higher than once estimated

Cases of drug resistant tuberculosis are higher than previously estimated and three nations — China, India and Russia — account for more than half of all cases worldwide, according to new research.

Multi-drug resistant tuberculosis (MDR-TB) are strains of the airborne disease that are resistant to at least two of the most important first-line drugs.

Researchers from the World Health Organisation (WHO) and the Centres for Disease Control and Prevention (CDC) in the United States, who conducted surveys in 79 countries, estimate there were 424 000 cases of MDR-TB in 2004.

”There is increasing drug resistance in some parts of the world, namely the former Soviet Union and China,” Dr Mario Raviglione, of the WHO, said in an interview.

He reported the finding in latest edition of the Lancet medical journal.

TB affects about nine million people each year and kills two million. Earlier estimates of MDR-TB were about 300 000 new cases annually.

The high prevalence of MDR-TB coincides with fast growing HIV infection rates in Eastern Europe and Central Asia. TB is one of the main opportunistic infections that kills HIV/Aids sufferers.

The team of researchers, which included scientists from the Prince Leopold Tropical Institute in Antwerp, Belgium, found rates have declined in countries such as Latvia, the United States, Hong Kong and Cuba.

But there is an increase in certain parts of the world including Botswana and Tomsk Oblast in Russia.

”By having better data we are able to recalculate estimates of six or seven years ago,” said Raviglione.

Resistance to TB drugs, which makes the illness difficult to treat, occurs when the treatments are not used properly.

Raviglione warned MRD-TB is a precursor to XDR-TB, which was recently reported among HIV-infected people in South Africa.

XDR-TB, or extensive drug resistant TB, is resistant to three or more of the six classes of second-line drugs.

”MDR-TB is the preamble of XDR-TB,” said Raviglione.

Health experts have called for immediate strengthening of TB controls programmes in countries where drug resistant TB is a problem to increase their ability to diagnose the disease.

Drugs must also be available, administered under supervision and monitored for the entire course of the treatment.

”There are two lines of action that are important — strengthen the control programmes with what we have today and develop the tools for the future,” Raviglione said. – Reuters