Chapter 002. Global Issues in Medicine (Part 6) ppsx

Second, passive case-finding relies on the availability of health care services, which is uneven in settings where TB is most prevalent.. Third, patients with multidrug-resistant MDR TB

Chapter 002 Global Issues in Medicine

(Part 6)

Tuberculosis

Chapter 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 therapy using short-course isoniazid- and

rifampin-based regimens) was promoted in the early 1990s as highly cost-effective

by the World Bank, the WHO, and other international bodies Passive case-finding

of smear-positive patients was central to the strategy, and an uninterrupted drug

supply was, of course, deemed necessary for cure DOTS was clearly effective for most uncomplicated cases of drug-susceptible TB, but it was not long before a number of shortcomings were identified First, the diagnosis of TB based solely on smear microscopy—a method dating from the late nineteenth century—is not sensitive Many patients with pulmonary TB and all patients with exclusively extrapulmonary TB are missed by smear microscopy, as are most children with active disease Second, passive case-finding relies on the availability of health care services, which is uneven in settings where TB is most prevalent Third, patients with multidrug-resistant (MDR) TB are by definition infected with strains of

Mycobacterium tuberculosis resistant to isoniazid and rifampin; thus exclusive

reliance on these drugs is ineffective in settings in which drug resistance is an established problem

The crisis of antibiotic resistance registered in U.S hospitals is not confined to the industrialized world or to bacterial infections In some settings, a substantial minority of patients with TB are infected with strains resistant to at least one first-line anti-TB drug As an effective DOTS-based response to MDR

TB, global health authorities adopted DOTS-Plus, which adds the diagnostics and drugs necessary to manage drug-resistant disease Even before DOTS-Plus could

be brought to scale in resource-constrained settings, however, new strains of

extensively drug-resistant (XDR) M tuberculosis began to threaten the success of

TB control programs in already-beleaguered South Africa, for example, where

high rates of HIV infection have led to a doubling of TB incidence over the past decade

Tuberculosis and AIDS as Chronic Diseases: Lessons Learned

Strategies effective against MDR TB have implications for the management

of drug-resistant HIV infection and even drug-resistant malaria, which, through repeated infections and a lack of effective therapy, has become a chronic disease

in parts of Africa Indeed, examining AIDS and TB together as chronic diseases allows us to draw a number of conclusions, many of them pertinent to global health in general (Fig 2-3)

First, charging fees for AIDS prevention and care will pose insurmountable problems for people living in poverty, many of whom will always be unable to pay even modest amounts for services or medications Like efforts to battle airborne

TB, such services might best be seen as a public good for public health Initially, this approach will require sustained donor contributions, but many African countries have recently set targets for increased national investments in health—a pledge 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 <$0.50 (U.S.) per day, and costs continue to decrease to affordable levels for public health bodies in developing countries

Second, the effective scale-up of pilot projects will require the strengthening and sometimes rebuilding of health care systems, including those charged with delivering primary care In the past, the lack of health care infrastructure has been cited as a barrier to providing ART in the world's poorest regions; however, AIDS resources, which are at last considerable, may be marshaled 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, is invoked 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 reason doctors leave Africa is that they lack the tools to practice their trade there AIDS funding provides an opportunity not only to recruit physicians and nurses to underserved regions but also to train community health workers to supervise care for AIDS and many other diseases within their home villages and neighborhoods Such training should be undertaken even in places where physicians are abundant, since community-based, closely supervised care represents the highest standard of care for chronic disease, whether in the First World or the Third

Fourth, extreme poverty makes it difficult for many patients to comply with therapy for chronic diseases, whether communicable or not Indeed, poverty in its many dimensions is far and away the greatest barrier to the scale-up of treatment and prevention programs It is possible to remove many of the social and

economic barriers to adherence, but only with what are sometimes termed "wrap-around services": food supplements for the hungry, help with transportation to clinics, child care, and housing In many rural regions of Africa, hunger is the major coexisting condition in patients with AIDS or TB, and these consumptive diseases cannot be treated effectively without adequate caloric intake

Finally, there is a need for a renewed basic-science commitment to the discovery and development of vaccines; of more reliable, less expensive diagnostic tools; and of new classes of therapeutic agents This need applies not only to the three leading infectious killers—against none of which an effective vaccine exists—but also to many other neglected diseases of poverty