After 2015: infectious diseases in a new era of health and development

Abstract

Running over timescales that span decades or centuries, the epidemiological transition provides the central narrative of global health. In this transition, a reduction in mortality is followed by a reduction in fertility, creating larger, older populations in which the main causes of illness and death are no longer acute infections of children but chronic diseases of adults. Since the year 2000, the Millennium Development Goals (MDGs) have provided a framework for accelerating the decline of infectious diseases, backed by a massive injection of foreign investment to low-income countries. Despite the successes of the MDGs era, the inhabitants of low-income countries still suffer an enormous burden of disease owing to diarrhoea, pneumonia, HIV/AIDS, tuberculosis, malaria and other pathogens. Adding to the predictable burden of endemic disease, the threat of pandemics is ever-present and global. With a view to the future, this review spotlights five aspects of the fight against infection beyond 2015, when the MDGs will be replaced by a new set of goals for poverty reduction and sustainable development. These aspects are: exploiting the biological links between infectious and non-infectious diseases; controlling infections among the new urban majority; enhancing the response to international health threats; expanding childhood immunization programmes to prevent acute and chronic diseases in adults; and working towards universal health coverage. By scanning the wider horizon now, infectious disease specialists have the chance to shape the post-2015 era of health and development.

Keywords: Millennium Development Goals; Universal Health Coverage.

Figure 1.

The demographic transitions in Sweden (1750–2000) and Mexico (1900–2000), which are interlinked with the epidemiological transitions in these two countries. The fall in mortality, at first mainly from childhood infectious diseases, is followed by a decline in fertility, producing growing, ageing populations afflicted mainly by chronic, non-infectious diseases. Adapted from reference [2].

Figure 2.

Deaths from infectious diseases (plus maternal and nutritional disorders) and non-infectious diseases (including injuries) worldwide, 1990–2050. (a) Estimated deaths in 1990, 2010 and 2050. (b) Top 10 causes of death from infectious diseases in 2010. Figures above the bars are the numbers of pathogens causing the majority of deaths from each disease. (c) Proportion of deaths due to infectious and non-infectious diseases in low, low-middle, upper-middle and high-income countries in 2010 (World Bank classification). (d) Factors affecting percentage changes in the numbers of deaths worldwide, 1990–2010. The fall in death rates per capita (left) is offset by population growth (especially deaths from infectious diseases, centre) and ageing (especially deaths from non-infectious diseases, right). Data from references [3,4].

Figure 3.

Trends in direct financial assistance for health, 1990–2010, measured in US$ billions per year (log scale), with five of the principal areas of investment. NCD, non-communicable (non-infectious) diseases. Data from reference [10].

Figure 4.

The triangular relationship between nutrition, diabetes and tuberculosis, as investigated in reference [37].

Figure 5.

Infectious diseases in urban areas. (a) Annual number of fadeouts of measles (three or more consecutive weeks without a notified case) in relation to the population sizes of 54 towns and cities in England and Wales in the pre-vaccination era [49]. (b) Infant mortality in urban and rural areas of 90 countries worldwide. Most points lie above the diagonal line marking equal mortality in urban and rural areas, indicating that death rates tend to be higher in rural areas [50].

Figure 6.

A total of 2797 international health hazards by type and country, January 2001–September 2013. Eighty-four per cent were outbreaks of infectious diseases. Unpublished WHO data (2013).

Figure 7.

Worldwide coverage of eight vaccines used in the Expanded Programme on Immunization, 1980–2012 [66]. BCG, Bacille Calmette Guérin vaccine for TB; DTP3, third dose of diphtheria toxoid, tetanus toxoid and pertussis vaccine; HepB3, third dose of hepatitis B vaccine; Hib3, third dose of Haemophilus influenzae type B vaccine; MCV, measles-containing vaccine; PAB, protection at birth from tetanus; PCV3, third dose of pneumococcal conjugate vaccine; Pol3, third dose of polio vaccine.