The term global health has replaced tropical medicine and international health, disciplines linked to the history of colonialism, the post-independence era of the former European colonies, and the experience of development assistance (2,3). Global health is multidisciplinary, encompasses many elements besides development, and requires coordination of multiple parties, rather than direction by one organization or discipline. The increased technical and political complexity of global health, with many actors, including philanthropic and faith-based organizations, is reflected in its breadth, which covers diverse diseases but deals also with health systems issues and financing.

Global health reflects the realities of globalization, especially the increased movement of persons and goods, and the global dissemination of infectious and noninfectious public health risks. Global health is concerned with protecting the entire global community, not just its poorest segments, against threats to health and with delivering essential and cost-effective public health and clinical services to the world’s population. A fundamental tenet is that no country can ensure the health of its population in isolation from the rest of the world, as articulated in the Global Health Strategy of the United States Department of Health and Human Services (4). This vision reflects today’s health realities but was arrived at through milestones such as the 1993 World Development Report (Investing in Health) (5), the 2000 report of the Commission on Macroeconomics and Health (6), and the tremendous investment in HIV/AIDS begun earlier this century (7).

Three overlapping themes determine global health action: development, security, and public health. These themes provide the humanitarian and political bases for engagement by high-income countries in health matters internationally: for development, to promote health for stability, prosperity, and better international relationships; for security, to protect their populations against internal and external health threats; and for public health, to save lives worldwide and at home. Despite different requirements, organizations and agencies involved must adapt to global trends in socioeconomic development, fertility, population, and urbanization.

Recent estimates of the global incidence of disease suggest that communicable diseases account for ≈19% of global deaths (22). In Africa, 76% of deaths are still attributable to communicable, maternal, neonatal, or nutritional causes, compared with 25% in the entire world; conditions relevant to MDGs 4, 5, and 6 are responsible for 42% of years of life lost. Focus on infectious diseases remains necessary to prevent their global spread or recrudescence, save lives, enhance economic development, and increase health equity.

Major and persistent infectious disease threats, their global incidence, and some of the global health commitments made to address them are shown in the Technical Appendix. The 1993 World Bank report Investing in Health first highlighted the overwhelming role of HIV/AIDS, tuberculosis, and malaria in Africa (5), but only in the past decade have substantially increased investment and effort enabled measurable progress in these major infectious disease challenges. The world needs to maintain momentum to achieve ambitious health targets and implement recent scientific advances while simultaneously coping with economic austerity.

There is increasing pressure to use resources for biomedical interventions with the strongest evidence of efficacy. Efforts toward achieving an AIDS-free generation are centered around HIV treatment scale-up, prevention of mother-to-child transmission (including through immediate and life-long antiretroviral therapy for all HIV-infected pregnant women), medical male circumcision, HIV testing and counseling, and focus on key populations in which HIV infection is concentrated (23). The primary current research question in HIV/AIDS is how best to use antiretroviral therapy for individual health and for population-based prevention, and more specifically, whether immediate therapy upon early diagnosis would confer the greatest benefit (24,25). The commitment to virtual elimination of HIV disease in children (26) could usefully link new initiatives to traditional maternal and child health programs delivered through development funding.

Tuberculosis is decreasing in incidence in all regions of the world, although more slowly than expected in some regions (27). In the United States, 63% of all tuberculosis cases now occur in foreign-born persons, indicating likely acquisition of the infection outside the United States (28). The spread of drug-resistant tuberculosis and extensively drug-resistant tuberculosis (resistant to rifampin, isoniazid, quinolones and injectable antituberculous drugs) highlights global vulnerability and interrelatedness of health systems and challenges health equity. Key scientific advances concern better understanding of the role and use of antiretroviral therapy for persons with tuberculosis co-infected with HIV, new diagnostics with the potential to make case finding more effective, and less strikingly, new drugs.

The tools for combating malaria (insecticide-impregnated bed nets, indoor residual spraying of insecticide, artemisinin-based combination therapies, and intermittent preventive therapy for pregnant women) need further scale-up, but such tools are susceptible to development of resistance on the part of the vector or parasite, and evidence is accumulating that nets may be less durable than assumed (26,29). Despite the challenges, malaria elimination has risen up the global agenda in recent time.

Poverty-related diseases such as the 17 conditions categorized as neglected tropical diseases have also received increased investment, especially those for which mass drug administration offers a control strategy (30,31). A concern must be that some major causes of illness and death, such as visceral leishmaniasis and African human trypanosomiasis, remain overshadowed and unaddressed.

Two groups of diseases meriting global health attention are those that are epidemic prone or vaccine preventable, including influenza. The 2009 pandemic of influenza A(H1N1) demonstrated the global nature of the threat, as well as the need to consider strategies for provision of vaccine for all countries (32). Dengue and yellow fever are the major mosquito-borne viral infections, and both illustrate the concept of emerging infections promoted by diverse factors, such as urbanization, population growth, inadequate environmental hygiene, and vector resistance to insecticide. In recent years, large outbreaks involving a specific arbovirus, chikungunya virus, have affected the east coast of Africa and islands in the Indian Ocean with importation into Europe.

The second decade of this century has been designated as the decade of vaccines (33). The opportunity exists for a notable effect on the 2.5 million deaths of children annually from vaccine-preventable diseases, including through use of new vaccines for prevention of rotavirus and pneumococcal infection, and by strengthening routine services. Vaccination against type A meningococcal meningitis in the Sahel and against hepatitis B virus and human papillomavirus illustrate the unrivaled possibilities in terms of controlling previously deadly epidemics or virus-induced cancers. A major unfinished priority is polio eradication; this goal is particularly threatened by funding shortfalls and ongoing transmission in Pakistan, Afghanistan, and Nigeria, which have seeded infection in other countries in which polio had been eliminated (34).

Lack of access to water and sanitation highlights some of the greatest inequities in global health. Approximately 1 billion persons worldwide do not have clean drinking water, and ≈2.5 billion persons have to openly defecate, which is an affront to human dignity (35). Large epidemics of waterborne diseases continue to occur, as exemplified by ongoing cholera transmission in Haiti (36). It is difficult to explain why investment in separating human drinking water from human feces, the basis of the nineteenth century public health revolution in Europe and North America, has not been a higher political or development priority in resource-poor settings.

The high-level meeting on noncommunicable diseases at the General Assembly of the United Nations in 2011, only the second such meeting devoted to health, emphasized how these diseases now dominate health worldwide (37). More than 60% of preventable deaths worldwide are now attributable to noncommunicable diseases (cardiovascular diseases, cancers, diabetes, and chronic respiratory diseases); in low-income and middle-income countries, 48% of such deaths occur in persons <70 years of age, compared with 26% in high-income countries (38). The incidence of these conditions is also increasing rapidly in Africa, a region in which urbanization and population growth are most extreme.

The risk factors for noncommunicable diseases are associated with urbanization and altered lifestyles, especially smoking, physical inactivity, air pollution, unhealthy diet, and excessive alcohol use. Hypertension, obesity, and increased cholesterol levels are measurable indicators predicting adverse outcomes, and specific chronic infections, such as those with hepatitis B virus and human papillomavirus, are linked to certain cancers. Injuries and mental health were omitted from the 2011 United Nations agenda despite the increasing incidence of these conditions; each year >5 million deaths worldwide result from injuries and violence (39), and ≈1.3 million are caused by road traffic injuries. Mental and behavioral disorders are considered the largest contributor to years lived with disability (22).

Global funding for noncommunicable diseases is minimal and coordination is limited, although opportunities exist for integrating approaches to communicable and noncommunicable diseases. Implementation of surveillance to assess incidence and needs along with selected policy interventions to address them will have the greatest immediate effect for the least cost. Examples of such policies include restricting tobacco sales and access, raising tobacco taxes, limiting unsafe use of alcohol, enacting motorcycle helmet and seat belt laws, and reducing salt and trans fats in commercial food products. To encourage countries to take action, WHO is defining population-level targets for noncommunicable diseases and associated risk factors for program implementation (37). Experience with HIV/AIDS treatment scale-up (40) could provide useful lessons for a standardized approach to management of hypertension and diabetes, thereby enhancing cost-effectiveness; facilitating supervision, monitoring, and evaluation; and ensuring accountability.

Population growth, increased life expectancy of the world’s citizens, and decreased age-specific mortality rates in children and young adults, especially those for infectious diseases, have contributed to the altered global health landscape. The New Global Health concerns health in all countries and encompasses poverty alleviation, universal health security, and delivery of appropriate public health and clinical services, including for the increasing prevalence of noncommunicable diseases.

Equity, universal health coverage and access, and fairness in health financing are global aspirations likely to feature prominently in discussions about what comes after the 2015 MDG target date. The unfinished infectious disease agenda will remain a priority, but common approaches will have to address noncommunicable diseases, regulation of commerce in medical technologies and pharmaceuticals, health financing, and systems strengthening. An emerging topic will be surveillance for and mitigation of effects of environmental and climate change.

Surveillance will have to be strengthened globally to track exposure to risk factors for the major causes of disability and death, disease outcomes, and health systems responses. The past and on-going epidemiologic transitions mean that in many countries, the classic health indicators of international health (infant, under-5, and maternal mortality rates) no longer provide insight into population health. In addition, there is an urgent need for robust vital registration systems and accurate reporting of cause-specific mortality rates across all life stages.

We must not forget the current challenges facing the lowest-income countries, the needs of disenfranchised or displaced populations, societies threatened by conflict and humanitarian emergencies, and the urban and rural poor living conditions in the midst of plenty. Nonetheless, global health practice must adapt to globalization and the rapid evolution in health underway worldwide. For donor countries, this will require clear definition of expectations of development assistance and how this differs from other forms of global health engagement, especially for health security and noncommunicable diseases. How to provide appropriate coordination, the kind of leadership desired, and how to ensure the shared responsibility of funding beyond the traditional donors will all feature prominently. Global interconnectedness requires us to address the health of the planet’s entire population, irrespective of national borders. Engagement in global health is not simply a humanitarian concern but a priority for our collective well-being, efficient use of resources, and safeguarding our future.