Chapter 002. Global Issues in Medicine (Part 6)

TuberculosisChapter 158 offers a concise overview of the pathophysiology and treatment of TB, which is closely linked to HIV infection in much of the world. Indeed, a substantial proportion of the resurgence of TB registered in southern Africa may be attributed to HIV co-infection. Even before the advent of HIV, however, it was estimated that fewer than half of all cases of TB in developing countries were ever diagnosed, much less treated.Primarily because of the common failure to diagnose and treat TB, international authorities devised a single strategy to reduce the burden of disease. The DOTS strategy (directly observed...
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Chapter 002. Global Issues in Medicine (Part 6) Chapter 002. Global Issues in Medicine (Part 6) Tuberculosis Chapter 158 offers a concise overview of the pathophysiology andtreatment of TB, which is closely linked to HIV infection in much of the world.Indeed, a substantial proportion of the resurgence of TB registered in southernAfrica may be attributed to HIV co-infection. Even before the advent of HIV,however, it was estimated that fewer than half of all cases of TB in developingcountries were ever diagnosed, much less treated. Primarily because of the common failure to diagnose and treat TB,international authorities devised a single strategy to reduce the burden of disease.The DOTS strategy (directly observed therapy using short-course isoniazid- andrifampin-based regimens) was promoted in the early 1990s as highly cost-effectiveby the World Bank, the WHO, and other international bodies. Passive case-findingof smear-positive patients was central to the strategy, and an uninterrupted drugsupply was, of course, deemed necessary for cure. DOTS was clearly effective formost uncomplicated cases of drug-susceptible TB, but it was not long before anumber of shortcomings were identified. First, the diagnosis of TB based solely onsmear microscopy—a method dating from the late nineteenth century—is notsensitive. Many patients with pulmonary TB and all patients with exclusivelyextrapulmonary TB are missed by smear microscopy, as are most children withactive disease. Second, passive case-finding relies on the availability of health careservices, which is uneven in settings where TB is most prevalent. Third, patientswith multidrug-resistant (MDR) TB are by definition infected with strains ofMycobacterium tuberculosis resistant to isoniazid and rifampin; thus exclusivereliance on these drugs is ineffective in settings in which drug resistance is anestablished problem. The crisis of antibiotic resistance registered in U.S. hospitals is notconfined to the industrialized world or to bacterial infections. In some settings, asubstantial minority of patients with TB are infected with strains resistant to atleast one first-line anti-TB drug. As an effective DOTS-based response to MDRTB, global health authorities adopted DOTS-Plus, which adds the diagnostics anddrugs necessary to manage drug-resistant disease. Even before DOTS-Plus couldbe brought to scale in resource-constrained settings, however, new strains ofextensively drug-resistant (XDR) M. tuberculosis began to threaten the success ofTB control programs in already-beleaguered South Africa, for example, wherehigh rates of HIV infection have led to a doubling of TB incidence over the pastdecade. Tuberculosis and AIDS as Chronic Diseases: Lessons Learned Strategies effective against MDR TB have implications for the managementof drug-resistant HIV infection and even drug-resistant malaria, which, throughrepeated infections and a lack of effective therapy, has become a chronic diseasein parts of Africa. Indeed, examining AIDS and TB together as chronic diseasesallows us to draw a number of conclusions, many of them pertinent to globalhealth in general (Fig. 2-3). First, charging fees for AIDS prevention and care will pose insurmountableproblems for people living in poverty, many of whom will always be unable to payeven modest amounts for services or medications. Like efforts to battle airborneTB, such services might best be seen as a public good for public health. Initially,this approach will require sustained donor contributions, but many Africancountries have recently set targets for increased national investments in health—apledge that could render ambitious programs sustainable in the long run.Meanwhile, as local investments increase, the price of AIDS care is decreasing.The development of generic medications means that ART can now cost Second, the effective scale-up of pilot projects will require thestrengthening and sometimes rebuilding of health care systems, including thosecharged with delivering primary care. In the past, the lack of health careinfrastructure has been cited as a barrier to providing ART in the worlds poorestregions; however, AIDS resources, which are at last considerable, may bemarshaled to rebuild public health systems in sub-Saharan Africa and other HIV-burdened regions—precisely the settings in which TB is resurgent. Third, a lack of trained health care personnel, most notably doctors, isinvoked as a reason for the failure to treat AIDS in poor countries. The lack is real,and the brain drain, which is discussed below, continues. However, one reasondoctors leave Africa is that they lack the tools to practice their trade there. AIDSfunding provides an opportunity not onl ...