Ebola is on the world’s news agenda again this week. If a novelist had thought of a way to narrate why global health matters, she could not have thought up a more fitting example. A (thankfully) slow spreading but scary, very deadly disease that gets everyone’s attention; a virus that can be contained in Lagos, Nigeria, but some American citizens are not so sure they are safe in New York. Beyond what is visible in the media right now  — the cycle of preventable suffering in Africa and fear adjustment reactions in the United States — lies a world of its own. It is called global health and, in just a decade, it has morphed from a few international agencies administering aid in far away places to a billion dollar industry trying to get a handle on the worlds biggest health challenges. Good intentions, unintended consequences, surprising successes and costly failures are all part of it. If we want to understand the slow response to the Ebola epidemic or why some countries are hit so much harder than others in West Africa, here is a start: Below are some excerpts from an essay I wrote in 2012 trying to explain this vast new landscape and why it matters. (The complete essay is here.)

What is Global Health?

As industry, technology, and the global spread of AIDS have made our world a much smaller place, our shared humanity becomes harder to deny. In recent years, the proposition that health is a social justice issue—one that enables all other development, from the healthy growth of individuals to economic productivity to national stability—has not only been recognized as visionary, it forms the backbone of the ongoing historic efforts we now call global health.

The term is fairly new—the field used to be called international health—and the change represents this new worldview. Global health today moves beyond infectious diseases in developing countries to focus on all health challenges, everywhere. It promotes comprehensive care and local empowerment. It asks for cooperative actions and solutions, not mandates for developing countries. It asks for shared responsibility for our shared welfare.

Why Health Matters

While the health of the world’s population has improved dramatically in the past century, the bounty has not been shared evenly. Roughly 90 percent of the world’s healthcare resources are used by only 10 percent of the world’s population. In Angola, 175 out of 1,000 children die in childbirth; in the United States, that number is 6.6. Similar to HIV/AIDS and tuberculosis, malaria predominantly infects people in low-income countries, and it kills about one million annually. Developing nations today also see a rise in chronic illnesses, such as cardiovascular diseases, diabetes and cancer.

Global health matters because to this day, millions of people die from preventable diseases simply because they are poor; malnutrition, combined with unsanitary or crowded conditions and a lack of vaccinations, medication and care, leaves them exposed.

Children are especially vulnerable: in 2010, 7.6 million children under the age of five died, a majority of them from curable diseases such as diarrhea, measles and malaria. The number is down from 12.4 million in 1990, which proves that some interventions are working, such as the distribution of bed nets that protect against malaria or the invention of a simple solution of salts, sugars and water that prevents dehydration from diarrhea. But too often effective prevention and treatment do not reach communities in need.

Such failures reveal our fragility. In 2007, Oswaldo Juarez moved to the United States from Peru to study English. First came the fevers and the wheezing fits. Then he started coughing blood. Several doctors had to be consulted before it became clear what was wrong with Juarez: he had tuberculosis. Not just simple tuberculosis, not just multidrug-resistant tuberculosis (MDR-TB) or extensively-drug-resistant tuberculosis (XDR-TB) – but XXDR-TB, a strain never before seen in the United States and untreatable with common antibiotics.

Juarez spent nearly two years in a Florida sanatorium, isolated from friends and family, undergoing a risky treatment of chemotherapy and other drugs, as Margie Mason reported for The Associated Press in 2009. Mason was a Nieman Fellow in global health reporting; her Nieman reporting project on global drug resistance led her to discover the case that the public had been unaware of until then. Juarez walked out of the hospital alive, but experts like Dr. David Ashkin, medical executive director of the State TB Hospital in Florida, told Mason, “He is really the future. These are the ones that we fear because I’m not sure how we treat them.” XDR tuberculosis killed 52 of the first 53 people diagnosed with it in South Africa a few years ago.

It is examples such as this one—or the rapid spread of the highly infectious SARS virus in 2003 from Hongkong to Taiwan to the U.S. and Canada—that illustrate how health challenges threaten not just the poor but everyone, everywhere.

Global health matters because in our co-dependent economies, with shared resources and a shared biology, our lives have never been more intimately intertwined. In fact, if a disease agent such as the one that caused the 1917/18 influenza pandemic would hit the world today, there would be no food deliveries within a few days, no medical drugs (most of which are imported), and almost no nation would be able to come to another’s rescue as they would all be responding to the emergency at the same time.

Health Takes Center Stage

As smart phones have taken hold in the developing world, virtual conversations are everywhere, connecting people through their shared interests rather than their economic circumstances. The Internet, social media and increased travel all create an awareness of the stark disparities that exist in the world, and with that bring, especially to a younger generation, a renewed desire to do the right thing, to make a difference in the world.

The Harvard physician and historian of science Jeremy Greene says that in recent years, “Global health has become a visible and apparently universal good for our times, a moral imperative that has captured the imaginations of many around the world—albeit often to quite different ends.” As a result, there is a striking mix of players in the field today. Health ministers, evangelical missionaries, human rights advocates, military generals, teenage social entrepreneurs, neo-liberal and progressive economists, medical anthropologists, epidemiologists, WHO bureaucrats, and pop and movie stars all find common ground in global health.

The many agendas that come together—from national security concerns to empathy and altruism to the promotion of economic stability to the desire to export democratic ideals, including fairness and equality—have enabled health to move from a back burner issue to center stage. Worldwide financial assistance from developed to developing nations, for example, more than tripled recently, from $7.6 billion in 2001 to $26.4 billion in 2008, with most of the increase going to health-related interventions.

Also, 30 years ago there were only three major international bodies designing international health policies and projects—WHO, the World Bank and the International Monetary Fund—as well as a few key non-governmental organizations. Today, there are thousands of Non-Governmental Organizations of all sizes plus several new big players, from the Gates Foundation to the Global Fund to Fight AIDS, Malaria and TB. To put this in perspective: The Gates Foundation’s annual global health budget recently surpassed that of WHO.

Not surprisingly, coordination is one of the biggest challenges in global health today.