The recent emergence of extensively drug resistant tuberculosis (XDR-TB) in South Africa is not only the result of poor treatment adherence by TB patients. It stems from years of neglect endured by TB programmes throughout sub-Saharan Africa.
The current scale of the region’s drug resistance challenge is poorly understood, and African TB programmes are so dilapidated many are at a loss to know how to respond.
“We don’t understand the extent of it, and whether it’s more widespread than anyone thinks,” admits the head of the World Health Organization’s (WHO) TB department, Dr Mario Raviglione. “And if we don’t know what has caused it, then we don’t know how to stop it,” he told the New York Times in February.
It has been widely acknowledged that the new deadly TB strain may have developed because of insufficient medication or because patients missed some of their treatments. This ignores the many factors known to have major impact on treatment adherence. These include social and economic factors, as well as weaknesses in the health care system itself — all widespread in sub-Saharan Africa. This means that even ‘compliant’ patients are at a high risk of TB recurrence, as well as developing and transmitting drug resistant strains.
The tendency of recent reports to focus on patient-related factors as the ‘cause’ of drug resistant TB, conveniently overlooks the pervasive systemic factors driving TB and drug resistance in Africa.
HIV infection increases the likelihood of active TB more than 50-fold, for example, an estimated one-third of the 24.5 million people living with HIV (PLHIV) in sub-Saharan Africa also have TB. To make matters worse, current diagnostic tests for TB often fail to detect the disease among PLHIV.
As a result of the high rate of HIV infection in the region — and an almost complete lack of TB infection control measures in health centres — the threat of spread of the new deadly TB strain is high. There are fears that should XDR TB spread among the HIV-positive population, it could wreak havoc among millions of people throughout sub-Saharan Africa, reversing gains made in TB control and antiretroviral programs.
The capacity for TB drug resistance testing is, ironically, better in South Africa than anywhere else in the region. If XDR-TB had emerged in Zambia, or Lesotho, or Zimbabwe, for example, we might never have known. And if it has already emerged elsewhere, we still might not know even today because of the relative inability to detect TB drug resistance.
More than anything else, what makes the reported South African cases so alarming is that it could indicate TB drug-resistance underlies the HIV epidemic throughout the region. The factors behind the emergence of drug resistant TB are by no means unique to South Africa, but are prevalent throughout neighbouring countries.
Eleven of the 15 countries with the highest TB incidence globally are in the sub-Saharan Africa region. Nevertheless, TB is regarded as far less of a health priority than HIV. In recent years annual spending on HIV programmes in the region has skyrocketed, while in the same period anti-TB efforts have received paltry increases in resources.
Responding to the challenge of drug resistance — and TB in general — will require re-building the basics of African TB programmes in a number of ways: Training and retaining health workers in sufficient numbers; strengthening diagnostic and laboratory facilities; maintaining continuous drug supplies (including second-line drugs for treating drug resistant forms of TB); introducing infection control measures to stop the spread of TB; and raising awareness among affected people and communities.
As a first step to rolling back the years of neglect, understanding the extent of the drug resistance problem and its interaction with HIV is paramount. Detailed population-based studies of TB drug resistance in Africa are urgently required.
Second, difficult questions must also be asked about whether current TB control strategies are sufficient to address TB drug resistance and TB/HIV co-epidemics in the context of Africa.
Not until these two question marks are lifted will investment by the international community ensure an appropriate response.