Changing disease burdens and risks of pandemics (GMT 3)

Drivers

Environmental degradation, climate change, and increased urbanisation, mobility and migration all influence public health,^[1][2] for example by raising the risk of the global transfer of infectious disease and exposing people to environmental hazards (GMTs 1, 2, 8, 10).^[3][4] Elderly and poor people are particularly vulnerable.

Environmental health risks include particulate matter; ozone; indoor air pollution; unsafe water and sanitation; contamination from waste, including from research activities; exposure to chemicals, lead, mercury and other heavy metals;^[3][5] and noise. Overall, 24 % of the global burden of disease and 23 % of premature deaths are attributable to environmental causes.^[6] Urban air pollution, especially ambient particulate matter and ozone, are set to become the main environmental cause of mortality worldwide by 2050.^[7][8] The Organisation for Economic Co-operation and Development (OECD) forecasts that the number of premature deaths from exposure to particulate matter in urban areas could more than double to 3.6 billion in 2050, most in China and India. Premature deaths from indoor air pollution, however, are likely to fall in coming years.^[6] Ozone has a marked effect on human health (Figure 1) and is the most damaging air pollutant to vegetation, including crops.

Although economic growth and improved social conditions have reduced poverty, improved nutrition and widened access to safe drinking water, basic sanitation and education, they have encouraged unhealthy lifestyles in the developed world and increasingly among the developing world’s rapidly growing middle class. As a result, non-communicable disease (NCD) and medical conditions, including cardiovascular disease, cancers, diabetes, mental disorders and obesity, now outweigh communicable ones.^[9]

By 2011, global average life expectancy reached 70 in 2011^[12][13] and is expected to rise to 75 by 2045–2050 (GMT 1).^[10] Older people, however, are more vulnerable to environmental hazards, spend more years living with injury and illness^[11] and are susceptible to conditions of ageing, notably dementia.

Economic inequality, poverty and food insecurity continue to affect health outcomes and shorten lives within and across countries. Today 1.2 billion people still live in extreme poverty while in 2011–2013, 842 million peoples did not get enough food to live active lives.^[14][15]

Rapid technological development creates both benefits and risks. Health services have and will benefit from bio-, nano- and information technologies (GMT 4), but their novelty means that the effects of their application on human and ecosystem health are little understood. Their wastes and emissions are of particular concern – for example, while the individual effects of the increasing number of chemicals, including pesticides, are relatively well-known, their impacts in combination remain largely unknown.^[4]

Figure 1: World premature deaths due to urban pollution from particulate matter and ground-level ozone (2000–2050)^[7]

Source: OECD environmental outlook to 2050 - [a] and [b]
Note: BRIICS countries are: Brazil, Russia, India, Indonesia, China, South Africa

Growing antibiotic resistance, partly due to evolution though overuse and over prescription, and the widespread use of antibiotics in intensive animal rearing are also culpable, is increasingly of concern, but research is lagging.^[4][16] Concerns exist over the profitability of developing narrow-, rather than broad-spectrum drugs, and of a rich-country bias preventing medical spending that benefits the developing world.

Competition for global resources is expected to indirectly impact health. Continued exploitation of global fish stocks, for example, and increased ocean acidification could remove this critical food source from vulnerable populations – marine fish currently provide 6 % of global protein (GMTs 9, 10).^[17]

Trends

Non-communicable disease. In 2008, NCDs accounted for 36 million premature deaths, and are likely to cause 55 million by 2030.^[18] Long predominant in developed countries, NCDs became the leading disease burden in developing countries in 2010 (Figure 3). Cardiovascular disease and cancers are the biggest cause of mortality worldwide^[19] and diabetes, to which the socially disadvantaged are most vulnerable, is projected to affect 471 million by 2035.^[20] Senile dementia currently affects 44 million people and is projected to rise to 135 million worldwide by 2050, with 96 million of them in developing countries.^[21]

Lifestyle NCDs are increasing but are preventable – tobacco accounts for almost 6 million premature deaths a year, projected to rise to 8 million by 2030; around 3.2 million annually are attributable to insufficient physical activity and about 1.7 million to low fruit and vegetable consumption.^[22]

Currently 10 % of the world’s adults are obese, and, in 2012, more than 40 million children under the age of 5 were either overweight or obese. In developing countries with emerging economies, particularly in urban areas, the rate of increase in these problems is 30 % higher than in developed ones.^[23]

Communicable disease. In spite of the ongoing decline of communicable diseases (Figure 2), they still pose a significant threat to human health and international health security, especially in developing countries.^[26] Even in developed countries, communicable diseases have not been completely eradicated, and in some cases their incidence is growing, mainly due to the emergence of drug-resistant disease strains. For example, tuberculosis has re-emerged in some developed countries where it had historically been reduced to very low levels.^[27] In 2012, 8.6 million people globally were living with tuberculosis, and 1.3 million people died from it. In the same year, there were 35.3 million people living with HIV/AIDS worldwide, and 1.7 million people died of AIDS-related illnesses, including 230 000 children. Due to better access to therapy, the number of new HIV infections and deaths due to AIDS is decreasing globally, while the number of people living with HIV/AIDS is increasing.^[28]

HIV/AIDS has received much attention in the developing world, but many developing countries face ‘neglected tropical diseases’, a group of parasitic and bacterial diseases such as dengue and leprosy. Vaccination programmes and other health responses for these diseases do exist, but they are often poorly and inadequately administered. Additionally, several contagious diseases persist despite the availability of an effective vaccine for over 50 years. One example is measles, a highly contagious disease that remains one of the leading causes of death among young children, particularly in developing countries.

Figure 2: The change in the global burden of disease and share of non-communicable diseases by world regions (1990–2030)^[24][25]

Source: IHME Global health data exchange database (left panel); WHO Global health estimates - [c] and [d] (right panel)
Note: DALY refers to Disability Adjusted Life Years, defined by WHO as “the sum of Years of potential life lost due to premature mortality and the years of productive life lost due to disability”.

Pandemics. Some infections have the potential to cause pandemics – made more likely by high levels of international travel and migration;^[29] the ability of some viruses to mutate rapidly and jump from animals to humans; and antibiotic resistance.^[30] The World Health Organization (WHO) warns that the world is 'ill-prepared to respond to severe pandemics … threatening public health emergency'.^[31]

Health inequalities. Although life expectancy and health have improved globally over the last decades, significant differences still exist between and within countries, urban and rural areas, and different income-level groups. Indeed, about 75 % of all premature deaths in 2010 occurred in developing countries.^[4]

Health care services also vary: there are 33 physicians per 10 000 people in Europe, 5.5 in southeast Asia and 2.5 in Africa. The high cost of medical care is another cause for concern – WHO suggests that around 150 million people face financial ruin each year from having to pay for medical services.^[32]

Implications

Changes in disease burden could strain health systems and costs, deepen inequalities and increase poverty. If current demographic, urbanisation and health trends continue (GMTs 1, 2) developing countries will have to deal with a multiple burden of NCDs, communicable disease and pandemics, especially in slums of burgeoning urban areas.^[33]

The finances of developing countries may be threatened by NCDs – in countries in all income groups, productivity losses from NCDs are already greater than public health spending. In 2013, WHO warned that business-as-usual will increase productivity losses and health care costs everywhere, with the cost of inaction far outweighing that of taking action.^[7][33]

In developed countries, costs related to ageing populations and health could increase fiscal pressure and affect social cohesion and well-being (GMT 1).^[34]

An integrated approach to health encompassing health inequalities, social, economic and environmental factors is key. Both WHO^[33] and the United Nation Development Programme^[35] agree that improving human development requires increased investment in health as well as infrastructure, education, and governance.

With more than 70 % of people projected to live in cities by 2050, good governance in urban areas will benefit both the environment and public health.^[3] In rural areas, the interactions of wildlife, domesticated animals and human health pose growing risks of disease, which should be tackled by addressing the connections between them and ecosystem health.^[36]

European countries improved public health in recent decades, and have relatively strong social safety nets and public healthcare systems. Nonetheless, significant health inequalities remain within and across countries – and have increased since 2006^[37], with poor families disproportionally affected by the recent economic crises.^[4]  In Europe, including Russia, NCDs cause 86 % of premature deaths,^[38] with ambient air and noise pollution and antibiotic resistance of particular concern.^[3][39]

The health impacts of climate change are of particular concern for the elderly and vulnerable^[40] while rising temperatures are also likely to bring new vector-borne diseases.^[4] These factors, coupled with the increasing cost of long-term care and the decline in informal care for the elderly, threaten the affordability of technical advances, unless the EU addresses the underlying causes of ill health, including the influence of an ageing population, globalisation and environmental degradation.^[4][36][41]