Epidemiology and challenges to the elimination of global tuberculosis

Abstract

Recent epidemiological indicators of tuberculosis (TB) indicate that the Millennium Development Goal of TB elimination by 2050 will not be achieved. The majority of incident cases are occurring in population-dense regions of Africa and Asia where TB is endemic. The persistence of TB in the setting of poor existing health infrastructure has led to an increase in drug-resistant cases, exacerbated by the strong association with human immunodeficiency virus coinfection. Spreading drug resistance threatens to undo decades of progress in controlling the disease. Several significant gaps can be identified in various aspects of national- and international-directed TB-control efforts. Various governing bodies and international organizations need to address the immediate challenges. This article highlights some of the major policies that lawmakers and funding institutions should consider. Existing economic and social obstacles must be overcome if TB elimination is to be a reachable goal.

Figure 1. DOTS five-part framework which provided a cost-effective public health strategy on both individual and societal levels

Building on the successes of DOT programs, the WHO and partner agencies developed a strategy for treatment of MDR-TB, termed “DOTS-Plus”, in 1999. The DOTS-Plus strategy adapts the core components of DOTS to the needs of patients with drug-resistant TB [5, 6].

Figure 2

Three key time points in achieving TB elimination by 2050 if all criteria set forth by the Stop TB Partnership are effectively obtained [27,28].

Figure 3. Estimated number of new TB cases in 2007

The five countries that rank first to fifth in terms of total numbers of cases in 2007 are India (2.0 million), China (1.3 million), Indonesia (0.53 million), Nigeria (0.46 million) and South Africa (0.46 million). The TB in such high burdened countries usually affects members in their economic prime. Besides the loss of productivity, the cost of treating TB in such areas may involve mean household spending of as much as 8---20 percent of annual household income [29]. Reprinted with permission from World Health Organization. Global Tuberculosis Control 2009. Geneva: World Health Organization 2009.

Figure 4. Antiretroviral therapy coverage in sub-Saharan Africa in 2007

Major progress in HIV testing has been undertaken in the African region compared to previous surveillance data. However, thirty seven percent (500,000) TB patients in the African region knew of their HIV status in 2007. Of the 250,000 HIV-positive TB patients in this region, only 100,000 were started on HIV anti-retroviral therapy (ART). The progress in HIV testing, which still requires improvement, is outpacing treatment with ART. If this continues, the TB epidemic will be sustained in these settings [23,26,33,62]. Reprinted with permission from [68]. World Health Organization. Antiretroviral therapy coverage in sub-Saharan Africa. http://www.who.int/hiv/data/art_coverage/en/index.html.

FIGURE 5. MDR-TB treatment outcomes in nine countries in a 2004 cohort

<>brThe number of patients in the cohort is shown under each bar. A notable feature in all categories is the prominent percentage of death and defaulted/failed treatment. Patients with MDR and XDR-TB have a notably greater amount of morbidity and mortality [37,38,39]. The countries that contain the highest amount of MDR-TB cases include India (131,000), China (112,000), Russian Federation (43,000), South Africa (16,000) and Bangladesh (15,000). Reprinted with permission from World Health Organization. Global Tuberculosis Control 2009. Geneva: World Health Organization 2009.