26 Februaray 2008Emma Marris
Drug-resistant tuberculosis is on the rise in much of the world, according to a World Health Organization (WHO) report released yesterday.
The WHO estimates that of the 9 million new cases of tuberculosis each year, about 5% are resistant to the standard treatment: a 6-month course of the 'first-line drugs' isoniazid and rifampicin. Eastern Europe and parts of China were hard struck by such multi-drug resistant tuberculosis (MDR-TB). Baku, Azerbaijan, held the record with a hair-raising 22.3% of new tuberculosis cases being MDR-TB.
For the first time, the WHO has analysed the incidence of extremely drug-resistant tuberculosis (XDR-TB). This form of the disease is also resistant to the drugs used when first-line treatments fail — drugs such as fluoroquinolone. The estimated 40,000 cases of XDR-TB that hit globally per year (less than 0.5% of 9 million) are very difficult to cure: the standard phrase used is "virtually untreatable".
The report looked at more than 90,000 patients with tuberculosis in 81 countries; that is more data than in previous reports, although coverage of some areas, especially Africa, is still spotty.
WHO officials called for more investment in fighting drug-resistant forms of tuberculosis. "If we don't face the problem of tuberculosis frontally, we are not going to succeed in many parts of the world; and we are letting MDR-TB and XDR-TB simply grow unattended," says Mario Raviglione, director of the WHO's Stop TB department.
Despite the increase of drug-resistant tuberculosis worldwide, there are some rays of hope, says Raviglione. In the Baltic countries that were hotspots for resistant tuberculosis ten years ago, analysis shows that MDR-TB is actually declining, he says. "When you invest, when you commit, then it is possible to deal with MDR-TB and make it decline." Still, more money is needed, he says.Underestimated
Tuberculosis is usually treated with a combination of drugs so that if a strain is immune to one, it will be killed by the other. But incomplete treatment regimes and use of inappropriate drugs have selected for drug-resistant strains.
According to a recent study by Willem Sturm, a microbiologist at the University of KwaZulu-Natal, South Africa could have avoided its harrowing 2005 outbreak of XDR-TB in HIV-positive people if it had put more resources into surveillance of which strains were developing resistance to which drugs (See The evolution of a killer).
The WHO has been criticized in the past for not paying sufficient attention to drug resistance. "I think the WHO underestimated for quite a while on the impact of drug-resistant tuberculosis," says Jim Kim, chief of the Division of Social Medicine and Health Inequalities at Brigham and Women’s Hospital in Boston, Massachusetts. Back in the 1990s, says Kim, "There were people at the WHO who said it would never get above 1%, would never be a problem." Kim and researchers at the Boston-based medical charity Partners in Health argued otherwise, he says. "I think now the global community is in full agreement."
Partners in Health announced yesterday that they had received a US$4 million grant from the pharmaceutical company Eli Lilly in Indianapolis, Indiana, to train health workers in ten former Soviet Republics on how to deal with MDR-TB. These places have become a hotspot for drug-resistant tuberculosis, in part because of a shortage of drugs when communism collapsed, and high incarceration rates in jails that became breeding grounds for the bacteria.
