Extensively Drug Resistant TB (XDR-TB) is emerging as an ominous global health threat. The World Health Organization (WHO) and the United States Centers for Disease Control and Prevention (CDC) have now identified XDR-TB cases in all regions of the world, and global health authorities have launched an intensive response to escalating global TB resistance. XDR-TB treatment is extremely complicated, with some strains virtually untreatable with current medicines.
XDR-TB has become a frequent international news story, beginning with the August 2006 report of an outbreak of particularly virulent XDR-TB in KwaZulu-Natal, South Africa in which 52 of 53 patients died, on average within 25 days of diagnosis. XDR-TB has claimed nearly 300 lives in South Africa to date. The recent story of a U.S. attorney who traveled to Europe and back with XDR-TB confirms that borders cannot confine the potential spread of this airborne disease.
The spread of XDR-TB is a man-made tragedy. So long as TB is treated with a long, complex, decades-old drug regimen, drug resistance will continue to develop. The threat cannot be fully avoided until health care workers have a new, faster-acting drug regimen that patients can more easily complete.
Today, after nearly a half-century lapse in TB drug development, research is underway to deliver new, novel TB drugs that will be effective against drug-susceptible and drug-resistant strains. A shorter regimen, reliably administered, would minimize the potential for further resistance by reducing high non-compliance.
Progress in developing new drugs, diagnostics, and vaccines for TB is being galvanized by public-private partnerships, such as the TB Alliance, supported by philanthropies and governments, but eliminating all forms of TB demands the combined efforts of governments and research, pharmaceutical and health care communities worldwide.
The WHO and the Stop TB Partnership have launched a two-year $2.15 billion response plan that, if fully funded, could prevent hundreds of thousands of cases of drug-resistant tuberculosis (TB) and save 134,000 lives.
The plan emphasizes the urgent need to boost basic TB control and target investment in key areas, including: strengthening programs to treat drug- resistant TB; building capacity in diagnostic laboratories; expanding infection control and surveillance; and funding research into new and improved diagnostics, drugs and vaccines.
The plan reinforces the mission of the TB Alliance, a founding member of the Stop TB Partnership, to develop new TB drugs that will shorten treatment, be effective against susceptible and resistant strains, be compatible with antiretroviral therapies for those HIV-TB patients currently on such therapies, and improve treatment of latent infection.
Note:
MDR-TB is a form of TB that does not respond to the standard treatments and is defined as TB resistant to the main first-line drugs, isoniazid and rifampicin. There are an estimated 450,000 new cases of MDR-TB every year. Multidrug resistance emerges when there is mismanagement of drugs and under-investment in quality TB control. It can also be spread from one person to another. The cost of treating MDR-TB can be 1000 times more than treating standard TB.
XDR-TB occurs when there is resistance to all of the most effective anti-TB drugs, and is defined as TB with MDR-TB resistance as well as resistance to any one of the fluoroquinolone drugs and to at least one of the three injectable second-line drugs, amikacin, capromycin and kanamycin. Extensive drug resistance emerges through mismanagement of MDR-TB and can also spread from one person to another. According to the WHO, there are an estimated 25,000 to 30,000 new cases of XDR-TB every year. So far, 37 countries have confirmed cases of XDR-TB