XDR tuberculosis: an indicator of public-health negligence Annelies Van Rie
a 
and Donald Enarson bSee Articles
In the 1970s, short-course chemotherapy for tuberculosis offered the prospect of eradicating the disease from the world. By the late 1980s, it became clear that the HIV pandemic would lead to a rapid upsurge of tuberculosis in many countries, pose a major threat to tuberculosis control, and destroy the hope for eradication.1 During the 1990s, multidrug-resistant (MDR) tuberculosis received widespread attention after nosocomial outbreaks in the USA.2 In today's Lancet, Neel Gandhi and colleagues3 add a new chapter to the story, an outbreak of extensively drug-resistant (XDR) tuberculosis in South Africa, combining the three threats to tuberculosis control: rapid spread, HIV co-infection, and drug resistance.3
Gandhi and colleagues' study has important deficiencies, including missing information on resistance profiles to four of the six second-line drug classes4 and missing clinical data, precluding determination of risk factors for XDR tuberculosis. Nevertheless, the findings show the devastating effect of XDR tuberculosis on patients and health-care workers, its alarmingly high mortality rates in those co-infected with HIV, and rapid nosocomial spread.
XDR and MDR tuberculosis have the same root cause: negligent case-management and poorly functioning public-health services. Acquisition of drug resistance and transmission of drug-resistant strains contribute to their incidence. Causes include incorrect prescription of drug regimens, poor drug quality, erratic drug supply, non-adherence by patients, and poor infection control.5
The first report, in 2006, on the emergence of XDR tuberculosis worldwide estimated that 7% of samples of MDR tuberculosis are XDR tuberculosis.4 On the basis of recent reports of the global incidence of MDR tuberculosis,6 this estimate suggests an incidence of about 29
700 cases of XDR tuberculosis in 2004, 0?4% of the global burden of tuberculosis.The South African Medical Research Council, the US Centers for Disease Control and Prevention (CDC), and WHO proposed a seven-point emergency plan to combat XDR tuberculosis, similar to the national plan to combat MDR tuberculosis, developed in the 1990s by the CDC and their partners.7 The plan recommends undertaking rapid surveys of XDR tuberculosis, enhancing laboratory capacity and improving technical capacity to respond to the condition, implementing infection control, developing new drugs and rapid diagnostics, and increasing access to antiretroviral treatment.8 This emergency response targets outbreak management but does not offer a sound long-term solution. The report also highlights the urgent need to confront and correct poor performance of tuberculosis control programmes, and ensure strict control and proper use of first-line and second-line drugs. Indeed, the highest priority in stopping XDR tuberculosis must be its prevention. In 2004, only half (53%) of estimated cases worldwide were reported by health-care systems, and only 82% of these patients successfully completed treatment.9 In the area where the XDR tuberculosis outbreak took place, treatment completion rates were low and 39% of patients had MDR tuberculosis, indicating a public-health system in crisis. Treating MDR tuberculosis is feasible and effective, even in low-income countries, if based on sound public-health practice including good laboratory infrastructure, appropriate treatment regimens, proper management of side-effects, and sufficient resources to maintain adherence and prevent further amplification of resistance.10 In 2000, the Green Light Committee was created to provide a comprehensive programme for MDR tuberculosis, and to increase access to second-line drugs worldwide while ensuring their proper use to prevent increased drug resistance.11 Unfortunately, misuse of such drugs is a reality, and the prohibitive pricing that once prevented their widespread use is no longer in place. The second-line drugs are now widely accessible, unfortunately available in an unregulated manner and not only through well-functioning tuberculosis programmes.12
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Panos Pictures
There will be no magic bullet to tackle the emerging problem of XDR tuberculosis. Control of tuberculosis, complicated by extensive drug resistance and HIV, will be complex. As indicated by the XDR tuberculosis outbreak, a weak control programme could do more harm than good and create more cases of MDR and XDR tuberculosis than it can treat. New diagnostics, drugs, and vaccines are unlikely to be immediately available. The emergence of XDR tuberculosis should act as a stimulus to strengthen basic control measures and focus attention on why great scientific advances have had limited effect on the situation.13 The costs of neglecting tuberculosis control will continue to increase and inaction will lead us farther away from reaching global targets.
We declare that we have no conflict of interest.
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<!--end simple-tail-->Affiliations
a. Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599-7435 USA
b. International Union Against Tuberculosis and Lung Disease, Paris, France
Department of Epidemiology, University of North Carolina, Chapel Hill, NC 27599-7435 USA