The World Health Organization (WHO) said on Saturday that national governments and donors will need to spend a total of $2.15 billion between now and December 2008 in an ambitious programme of measures to contain the growing threat of multidrug-resistant and extensively drug-resistant tuberculosis (TB).
WHO says that hundreds of thousands of cases of drug-resistant TB can be prevented, and up to 134,000 lives saved, if national laboratory and surveillance systems are strengthened and a better supply of second-line TB drugs is established.
"We have sounded the alarm on the potential for an untreatable XDR-TB epidemic. Today we issue our response on behalf of all patients and communities whose lives are most at risk. It is an ambitious plan that must be fully supported if we are to keep a stranglehold on drug-resistant TB," said Dr Mario Raviglione, Director of the WHO Stop TB Department.
Multidrug-resistant TB develops when the TB bacterium develops resistance to several TB drugs as a result of low drug levels. If doses are missed or treatment interrupted, resistance can emerge rapidly. The bacterium adapts itself to reproduce in the presence of low drug levels, and gradually develops greater resistance to the drug.
MDR TB and XDR TB can also be transmitted from one person to another. This happens commonly in healthcare settings where large numbers of TB patients are housed together without good ventilation.
Multidrug-resistant TB is highly concentrated in countries with the fastest growing HIV epidemics, according to WHO. Eastern Europe, Russia, Central Asia and South Africa have serious problems, as do China and India.
However, the reasons for growing MDR TB problems vary from region to region. Although MDR TB is commonly ascribed to poor adherence to TB therapy, a recent study in China showed that MDR TB cases were overwhelmingly associated with poor infection control, not poor adherence in people already receiving TB treatment.
In Russia, MDR TB is a growing problem because of the high burden of TB infection in the prison system, together with disjointed and inconsistent treatment using out of date drugs and poor infection control in prisons.
In India the unsupervised use of second-line drugs in first-line treatment by private practitioners has contributed to a growing number of MDR TB cases.
In southern Africa the TB epidemic is intimately associated with the HIV epidemic, and XDR TB has emerged in South Africa almost entirely among HIV-positive patients. While TB can be treated successfully in HIV-positive people, especially those who are already receiving antiretroviral therapy, MDR and XDR TB are difficult to treat and result in rapid progression to death. Several international TB experts have warned that if XDR TB continues to spread in HIV-positive people in southern Africa, it has the potential to undermine the improvements in health delivered by growing access to antiretroviral treatment. South Africa alone estimates that it could face 600 cases of TB in 2007.
Proposals for strengthening TB control
Greater laboratory capacity is needed in order to diagnose TB more quickly. Improvement of drug susceptibility testing and widening of its availability will be essential in containing MDR TB, as will more rapid surveillance of drug susceptibility in new TB cases. Surveillance detects what proportion of a random sample of new cases in the population have drug resistance, and can show which drugs are less likely to be effective in second-line treatment in specific countries. Surveillance also needs to be expanded in order to understand better the links between MDR TB, XDR TB and HIV.
WHO and its partners will also need to hammer home the message about the importance of infection control in health care settings, the global response plan states. More attention is also needed to infection control in the community in settings with high HIV prevalence, such as southern Africa. Similarly important is infection control in `congregate` settings, such as prisons, schools and detention centres.
Greater technical assistance will be provided to countries with MDR TB problems, and national plans for dealing with MDR TB should be reviewed by experts from the Stop TB programme, especially where there is a high risk of XDR TB and wherever HIV prevalence is high. Countries that need assistance in planning for the next Global Fund grant-giving round should get it, the plan says, because this will be a crucial source of funding for national efforts to control MDR TB.
Stronger regulation of second-line TB drugs, greater promotion of the use of first and second-line drugs of sound quality, and faster supply of buffer stocks of second-line drugs to countries will be important too.
Advocacy for MDR TB control also needs to be stepped up, and healthcare providers need to understand the Stop TB Programme’s International Standards for Tuberculosis Care, since adherence to these standards is likely to reduce the incidence of MDR TB.
Progress on fundraising
Last November at the 37th World Conference on Lung Health international TB experts called for $15 million in emergency funding to counter the immediate threat of an explosion of XDR cases in southern Africa, as part of a larger $95 million package of measures. So far only half of that sum has been pledged by major international donors.
The $2.15 billion in spending required between now and the end of 2008 will require significant support from the Global Fund to Fight AIDS, Tuberculosis and Malaria. It will also require national governments to make significant financial commitments of their own, particularly in countries such as China, Russia and Kazakhstan.