Although the Sustainable Development Goals (SDGs) seek to end the tuberculosis epidemic altogether (WHO 2015a, 2015c), the decline in incidence has been disappointing. The internationally agreed targets for TB, embraced in the United Nations (UN) Millennium Development Goals (MDGs), sought “to halt and reverse the expanding incidence of tuberculosis by 2015,” and this target has been met to some extent in all six WHO regions and in most, but not all, of the world’s 22 high-burden countries (WHO 2014c).ĭespite progress, major gaps persist. By 2015, an estimated 49 million lives had been saved (WHO 2016a). Between 19, absolute global mortality from TB declined 18.7 percent, from 1.47 million to 1.20 million (Lozano and others 2012) and by 22 percent between 20 (WHO 2016a). Thanks in part to these efforts and national and international investments, much progress has been made in TB control over the past several decades. The DOTS strategy to control tuberculosis promotes standardized treatment, with supervision and patient support that may include, but is far broader than, direct observation of therapy (DOT), where a health care worker personally observes the patient taking the medication (WHO 2013a). This evidence has been central to the global promotion of the WHO and Stop TB Partnership policy of directly observed therapy, short course (DOTS) strategy, the package of measures combining best practices in the diagnosis and care of patients with TB (UN General Assembly 2000).
The reality in many countries is more complex, and overall the decline in incidence (only about 1.5 percent per year) has been unacceptably slow.Ĭhemotherapy for TB is one of the most cost-effective of all health interventions (McKee and Atun 2006). The premise is that, if patients with active disease are cured, mortality will disappear, prevalence of disease will decline, transmission will decline, and therefore incidence should decline. The basic strategy to combat TB has been, for 40 years, to provide diagnosis and treatment to individuals who are ill and who seek care at a health facility. Modeling suggests that more effective vaccines will likely be needed to drive tuberculosis toward elimination in high-incidence settings. Although bacille Calmette–Guérin (BCG) remains the world’s most widely used vaccine, its effectiveness is geographically highly variable and incomplete. The time between the onset of disease and when diagnosis is made and treatment is initiated is often protracted, and such delays allow the transmission of disease. More sensitive methods of diagnosing TB and detecting resistance to drugs have recently become available, although they are more expensive. In some areas, the incidence of drug-resistant TB, requiring even longer treatment regimens with drugs that are more expensive and difficult to tolerate, is increasing.ĭiagnosis in LMICs is made primarily by microscopic examination of stained smears of sputum of suspected patients however, smear microscopy is capable of detecting only 50–60 percent of all cases (smear-positive). These long drug regimens are challenging for both patients and health care systems, especially in low- and middle-income countries (LMICs), where the disease burden often far outstrips local resources. Treatment of TB disease requires multiple drugs for many months.
The risk of progression to TB disease after infection is highest soon after the initial infection and increases dramatically for persons co-infected with HIV/AIDS or other immune-compromising conditions. One of the challenges of TB is that the pathogen persists in many infected individuals in a latent state for many years and can be reactivated to cause disease. Only about 10 percent of individuals infected with Mtb progress to active TB disease within their lifetime the remainder of persons infected successfully contain their infection. Tuberculosis is an infectious bacterial disease caused by Mycobacterium tuberculosis (Mtb), which is transmitted between humans through the respiratory route and most commonly affects the lungs, but can damage any tissue. One-third of these new cases (about 3 million) remain unknown to the health system, and many are not receiving proper treatment. The World Health Organization (WHO) estimates that there are about 10.4 million new cases and 1.8 million deaths from TB each year. Despite 90 years of vaccination and 60 years of chemotherapy, tuberculosis (TB) remains the world’s leading cause of death from an infectious agent, exceeding human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) for the first time (WHO 2015b, 2016a).
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