Global health has been defined as ‘health problems, issues, and concerns that transcend national boundaries, may be influenced by circumstances or experiences in other countries, and are best addressed by co-operative actions and solutions’
There are numerous and increasing examples of such ‘boundary transcending problems’, like the flow of migrant workers who suffer from specific health problems (including distress and mental health conditions)
While some global health issues are well described, like the outbreaks of emerging or re-emerging infectious diseases (Box 22.1), little is known about others such as the massive exposure in low-income countries to environmental toxins such as arsenic, asbestos and air pollutants
The health effects of climate change are yet to be accurately defined
Some health problems are pandemic in nature, such as the current explosion of obesity and diabetes affecting both low- and high-income countries. The relative contribution of the various causes are still largely unknown; the new paradigm of ‘built environment’, incorporating notions of decreased physical exercise and outdoor activities due to changes in town planning—in addition to changes in food habits—has been proposed.
Tobacco-related effects continue as the main example of premature death, disability and chronic disease due to a single cause, and are expected to increase in low-income countries if effective measures against the use of tobacco are not taken
As the dramatic example of the effects of the drug thalidomide showed, it is important to identify early signals of negative impacts on health and rigorously assess their likely significance
Box 22.1 : Emerging and Re-emerging Infectious Diseases
Emerging infectious diseases are those that have been recently discovered, have increased in humans over the past two decades, or threaten to increase in the future.
Re-emerging infections are infectious diseases which have increased (previously having diminished in incidence) because of ecological changes, public health decline, or development of drug resistance.
Six major factors have contributed to their emergence or re-emergence:
1. Changes in human demography and behaviour (e.g. immunosuppression, ageing population, migration, risky behaviours)
2. Advances in technology and changes in industry practices (e.g. air conditioning cooling towers, changes in food processing, changes in rendering)
3. Economic development and changes in land use patterns (encroachment on the tropical rainforests, conservation efforts, climate changes)
4. Dramatic increases in volume and speed of international travel and commerce of people, animals and foodstuffs
5. Microbial adaptation and changes
6. Breakdown of public health capacity to address infectious diseases.
In most instances, the emergence of a specific agent results from a complex interaction of several factors.
Examples of emerging and re-emerging infections are given in Chapter 20.
Global health has been defined as ‘health problems, issues, and concerns that transcend national boundaries, may be influenced by circumstances or experiences in other countries, and are best addressed by co-operative actions and solutions’ (United States Institute of Medicine; see also Skolnick 2008). Interest in global health usually starts with the following observations.
There have been major improvements in health. Average global life expectancy has increased from 50 to 67 years since 1960; smallpox has been eradicated and deaths from measles fell by 48%, from 871 000 in 1999 to an estimated 454 000 in 2004.
There are even larger disparities in health than before. There are over 6 billion people in the world, 1 billion of whom can expect to lead a long and healthy life, but 5 billion are not so fortunate. For example, a child born in Japan has a life expectancy of 82 years, but one born in Swaziland will only live an average of 32 years. Maternal mortality rates range from 830 per 100 000 births in African countries to 24 per 100 000 births in European countries.
Health and disease have no borders. Health issues are not confined within national or regional borders. For example, an outbreak of severe acute respiratory syndrome in China in 2002 rapidly spread across the globe and within 8 months caused 8422 probable cases and 916 deaths in 29 countries. Control programmes need to be approached at an international level.
In the examples that follow all components of the definition above are fulfilled—these are health problems that not only ‘transcend the boundaries’ or have a worldwide dimension, but comprise issues that require concerted international action involving several institutions at different levels. Box 22.2 gives some additional information on the background global context.
Box 22.2 : The Global Context: Carrying Capacity, Biodiversity and Policy Responses
Carrying Capacity
Man’s activities of production and consumption affect not only our local environment but the environment of whole regions and the entire planet. Given the large scale of such activities in an increasingly globalized world, certain polluting or resource depleting activities that the carrying capacity of the local environment used to absorb now result in overload or contamination of global proportions. One of the best recognized examples in the twentieth century has been the devastating effect of acid rain on natural ecosystems whose ability to absorb and eliminate sulphuric acid was overwhelmed. The carrying capacity amounts to some 10 hectares for every person for the richest countries compared with only 2.5 hectares per person on a global average. Thus, on this and other measures there is not enough land to support the world’s population at the level of consumption enjoyed by the most industrialized countries. Of course, there is no widespread enthusiasm to reduce levels of consumption. On the contrary, there are widespread aspirations to increase industrial production and employment and to reduce, or eliminate, poverty. Various attempts have been made to estimate how many people can comfortably and sustainably live on this planet, based on some reasonable compromise between the (low) current average standard of living and the high average in the richest countries. Realistic estimates based on food production, water usage, energy consumption and the integrated footprints fall mostly in the range of 3–5 billion people. With a world population of 6 billion and projected increases to at least 10 billion before any prospect of levelling off, the sustainable carrying capacity of the planet is already being exceeded.
Biodiversity
As pressure on land has increased in the past 100 years, the rate of extinction has accelerated. It is estimated that 20–50% of species present 100 years ago will have become extinct by 2100, with the rate of loss accelerating from now until then. Many species are lost as biodiverse tropical rainforests are depleted by clearance and burning. This has practical consequences on human health by affecting food and drugs. Medicines have been identified and developed from tropical plants, and pharmacological possibilities for numerous species have not been explored. In the case of food, we have in the past relied on the cross-breeding of food crops with wild strains to maintain productivity and resistance to pests, and will no doubt need to continue to do this, whatever achievements arise from genetic modification in laboratories.
Policy Responses
The examples in the text have been selected to illustrate the wide range of environmental impacts on health. Our choice of modes of transport has both local and global impacts. Our energy consumption has an impact via its contribution to global warming. Toxic chemicals in the environment may cause local problems or be bioaccumulating and thus contribute to remote risk. In a parallel manner, policy instruments for preventing adverse environmental impacts operate on various levels. At a global level international conventions play a major role, although the important and potentially expensive ones are the most difficult to get all parties to agree to and ratify. The Kyoto agreement on limiting climate change gases will remain in limbo as long as the major polluters refuse to ratify it. Regulation at national and, for the European Union, a European level is embodied in directives, regulations and policies such as, in the United Kingdom, the national ambient air quality standards (NAAQS). Local initiatives prompted by the Rio de Janeiro meeting on environment and development have become an important focus for both local authority initiatives and the involvement of civil society. The so-called La21, or Local Agenda 21, developed as an idea intended to catalyse local environmental initiatives. Finally, industrial undertakings by their very size can have large environmental impacts by virtue of employment or pollution, or make products which have significant environmental impacts. Responsible corporate and product stewardship can be implemented to seek to reduce adverse environmental (or environmental health) impacts. This may be represented by adherence within the worksite to quality standards such as the Eco-Management and Audit Scheme or ISO 14 000 environmental quality schemes, or the adoption of ‘cradle to grave’ product stewardship initiatives, ensuring that raw materials such as wood are derived from sustainable sources, recycling is maximized, and products are designed so that they can be recycled.
Bangladesh is often used as a case study because it exemplifies at least three health-related changes that are typical: massive migration (mainly of men) towards rich countries such as Dubai and Qatar; susceptibility to the effects of climate change, partly related to changes in economic scenarios; and recent spectacular improvements in infant mortality. The first two phenomena match the definition of global health, because they result from global changes that transcend the boundaries of the country, and require cooperative action to be addressed. In addition, they are relevant to the work of physicians, and occupational and public health specialists in high-income countries, because an increasing number of migrants or refugees escaping from poverty or the effects of climate change may seek their help The third, a rapid decrease in infant mortality, has been obtained thanks to local action. It is an impressive, world-wide phenomenon seen also in several other low-income countries (see video section at end of chapter).
According to the fourth assessment report by the Intergovernmental Panel on Climate Change (IPCC) there is ‘high confidence’ that marine and coastal ecosystems in South and South East Asia will be affected by sea-level rise, leaving a million or so people at risk from flooding (Figure 22.1), whereas future climate change is likely to have severe effects on agriculture and water security (‘medium confidence’). The direct (short-term, i.e. hours or days) health risks from climate change are related to the physical hazards of floods, storms and associated infectious diseases. Less obvious or indirect (intermediate- and long-term, i.e. weeks to years) health risks are related to changes in food yields, population displacement as a result of sea-level rise and water shortages, mental health problems and other chronic diseases. The risk of malaria has been shown to be sensitive to variability in climate caused by the El Niño phenomenon in Central Asia, Africa and South America. Results, based on time-series analysis, suggest that the coupling between climate variability and cholera cycles has become stronger in recent decades.
