Seminars in respiratory and critical care medicine
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With 1.4 million deaths in 2011 and 8.7 million new cases, tuberculosis (TB) disease remains a global scourge. Global targets for reductions in the epidemiological burden of TB have been set for 2015 and 2050 within the context of the Millennium Development Goals (MDGs) and by the Stop TB Partnership. Achieving these targets is the focus of national and international efforts in TB control, and demonstrating whether or not they are achieved is of major importance to guide future and sustainable investments. This paper discusses the methods used to estimate the global burden of TB; estimates of incidence, prevalence, and mortality for 2011, combined with assessment of progress toward the 2015 targets for reductions in these indicators based on trends since 1990 and projections up to 2015; trends in TB notifications and in the implementation of the Stop TB Strategy; and prospects for elimination of TB by 2050.
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Drug-resistant strains of Mycobacterium tuberculosis have emerged as a major threat to global tuberculosis control. Despite the availability of curative antituberculosis therapy for nearly half a century, inappropriate and inadequate treatment has allowed M. tuberculosis to acquire resistance to our most important antituberculosis drugs. The epidemic of drug-resistant tuberculosis has spread quickly in some areas due to the convergence of resistant strains of M. tuberculosis in high-risk patients (e.g., those with human immunodeficiency virus/acquired immunodeficiency syndrome) and high-risk environments (e.g., hospitals and prisons). ⋯ Recently, cases of "totally drug resistant" tuberculosis have been reported. It is estimated that only 10% of all MDR-TB cases are currently receiving therapy and only 2% are receiving quality-assured drugs. This article reviews the management of MDR and XDR-TB and highlights the updated 2011 WHO guidelines on the programmatic management of drug-resistant tuberculosis.
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Semin Respir Crit Care Med · Feb 2013
Review Comparative StudyAdvances in the diagnosis of latent tuberculosis infection.
Accurate diagnosis of tuberculosis (TB) infection is an important component of tuberculosis control programs in many countries. Identification of persons with asymptomatic, or latent, tuberculosis infection allows for treatment of individuals at high risk for progressing to active disease so that the overall burden of tuberculosis disease is diminished. ⋯ Commercially available IGRAs have superior sensitivity and specificity compared with conventional tuberculin skin testingin some settings (particularly bacille-Calmette Guérin-vaccinated individuals). Also discussed are the performance characteristics of these tests in specific populations, including foreign-born persons from high-prevalence countries, close contacts of actively infected patients, immunocompromised populations, and health care workers.
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Latent tuberculosis infection (LTBI) refers to a circumstance in which viable Mycobacterium tuberculosis (MTB) bacilli are present in an individual but symptoms and signs of active disease are lacking, and the bacilli are relatively inactive metabolically. In favorable circumstances, some of these inactive bacilli resume greater metabolic activity and replication, leading to the development of active tuberculosis disease. ⋯ Adverse effects of treatment are considered, as are the special circumstances of human immunodeficiency virus-related LTBI, drug resistance, and use of TLTBI in the context of tumor necrosis factor alpha (TNF-α) inhibition. The review describes the main studies underpinning Centers for Disease Control and Prevention recommendations on use of the new 3-month isoniazid-rifapentine regimen and points to evolving data that may support future modification of those recommendations.
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Semin Respir Crit Care Med · Feb 2013
ReviewThe changing landscape of diagnostic services for tuberculosis.
During the last decade there has been a dramatic change in the laboratory approach to tuberculosis (TB) diagnosis in the developing world. This change began with the realization that acid-fast bacillus smear microscopy alone was totally inadequate to deal with the dual problems of human immunodeficiency virus (HIV)-associated TB and drug-resistant TB that threaten to undermine global progress in TB control. Subsequently, increased financial resources for TB laboratory services and the establishment of a systematic process for endorsement of new TB diagnostic tools and approaches by the World Health Organization (WHO) have led to rapid expansion of TB laboratory services and the availability of several new diagnostic tests that have been introduced. ⋯ The latter methodologies that include line probe assays and an automated cartridge-based real-time polymerase chain reaction (PCR)-based test are being scaled up at an unprecedented pace and are truly revolutionizing the diagnosis of drug-resistant TB. On the other hand, little progress has been made in the quest for a true point-of-care test for TB. Fortunately, this is being addressed in several discovery initiatives that hopefully will provide impetus for the development of rapid, accurate TB diagnostics for the lowest level of the health system.