Kin Cheung / Reuters

An outbreak of a deadly new coronavirus in Wuhan, China, has crippled the world’s second-largest economy and spread in 26 countries, causing more than 1,000 deaths and 43,000 laboratory-confirmed cases worldwide. A continent and two oceans away, the Ebola virus has been terrorizing the most heavily populated provinces of the Democratic Republic of Congo since August 2018. Even though the epidemic has slowed, three new cases have been reported in the past week.

When multiple international public-health emergencies occur at the same time, they may seem like evidence of microbes’ triumph over humankind. In fact, the opposite is true. Emerging infections like Ebola and the novel coronavirus—now dubbed COVID-19, as of yesterday—have a better platform to spread, somewhat ironically, because people are generally healthier than ever before.

For the first time in recorded history, bacteria, viruses, and other infectious agents do not cause the majority of deaths or disabilities in any region of the world. Since 2003, the number of people who die each year from HIV/AIDS has fallen by more than 40 percent. Deaths from malaria, tuberculosis, and diarrheal diseases have declined by more than 25 percent each. In 1950, there were nearly 100 countries, including almost every nation in sub-Saharan Africa, South Asia, and Southeast Asia, where at least one-fifth of children died—most of them from infectious diseases—before their fifth birthday. Today, there are none. The average life expectancy in developing countries has risen to 70.

Those who survive commonplace infectious diseases such as malaria or tuberculosis—or never contract them in the first place—are free to seek work in a complex economy, to reside in cities or migrate abroad in search of greater opportunities, to raise families and grow old with them, and to do all the other things that healthy people do. Yet humanity’s dramatic progress against specific infectious diseases has far outstripped the pace of investment in good health-care systems, responsive governance, dependable infrastructure, and the other more reliable guarantors of health. These basic factors are crucial, when a new disease such as COVID-19 suddenly emerges, in establishing how fast and how far it will spread and how may will perish because of it.

The progress against plagues and parasites throughout Europe and the United States in the 19th century extended globally after World War II with the increased availability of antibiotics, the development of more vaccines, and medical advances against diseases such as malaria. The horrors of World War II also inspired global leaders to build new institutions like the World Health Organization and UNICEF to promote economic development and confront humanitarian crises. In the decades that followed, international agencies, local governments, and foreign-aid donors worked together on successful campaigns to eradicate smallpox, vaccinate millions of children, and increase access in poor nations to lifesaving medicines for tuberculosis, HIV/AIDS, and other diseases.  

Even in countries with the most rudimentary health systems, the international investment in developing and disseminating medical advances has yielded longer lives, fewer dead children and grief-stricken families, and less human suffering more generally. Yet it has also made many nations more vulnerable to contagious viruses for which there are no available drugs to treat and no vaccines to prevent infections, and against which people have no preexisting immunity.

Successful outbreak control works like this: Patients report their symptoms to health-care workers. Those health-care workers then report unusual cases to local public-health officials who investigate the illness. Those officials may isolate ailing patients, identify others with whom they have come into contact, and monitor those individuals. The results of these investigations are reported to government officials, who communicate reliable information about the outbreak and its causes to the public and the press. That information enables those who are not sick to take measures, such as hand washing and avoiding crowds, to prevent themselves from getting infected and spreading the outbreak. The promise of reliable information and competent, supportive medical care convinces others who are suffering symptoms to come forward so that new cases are identified, tracked, and treated. This cycle continues until the virus stops infecting new people, the people already infected get well or perish, and the outbreak burns out.   

In short, shoe-leather public health and basic medical care—not miracle drugs—are generally what stop outbreaks of emerging infections like severe-acute respiratory syndrome and the Ebola virus. However, in many countries without responsive governments, open press, and rudimentary health-care systems, controlling an infection becomes much harder. Officials in repressive societies are more apt to rely on counterproductive censorship and quarantine measures that unduly interfere with citizens’ rights and spread distrust.

Meanwhile, demographic and societal changes are likely to amplify the consequences of an outbreak of a novel infection. From the time the Ebola virus was first identified until late 2013, that pathogen had killed fewer than 2,000 people over the course of 28 outbreaks, all in Central Africa.  But in an outbreak in West Africa from December 2013 to June 2016, Ebola killed nearly six times as many people in just two and half years. Eight cases of Ebola spread internationally, causing an international panic.  

Why did the 2013–2016 outbreak prove so lethal? Crowded cities are another product of humanity’s improving health. With lower rates of everyday infectious diseases, urban areas are less deadly to their inhabitants, and the population of cities in developing nations is growing faster than their urban infrastructure. The United Nations estimates that of the nearly 1.5 billion city dwellers added worldwide since 2000, 90 percent reside in lower-income countries. West Africa is now more than 70 percent urbanized, according to one leading estimate.

Emerging infectious diseases like Ebola are now less likely to burn out in rural villages and more likely to reach major population centers that have limited health systems as well as travel links that are the ideal incubators for outbreaks. This description fits Monrovia, Liberia, the city from which the first Ebola patient diagnosed in the United States had embarked on his journey to Dallas. It also applies to Beni, the mid-size city in northeastern Congo where Ebola rages, and Wuhan, the metropolis of 11 million where COVID-19 has so overwhelmed the health system that the virus is killing people at a rate 30 times greater than in the rest of China.

Further increasing the danger of outbreaks and epidemics is another by-product of better health: complacency. In 2013, less than 0.5 percent of international health aid was devoted to preventing infectious-disease outbreaks, and the portion of the World Health Organization budget funded by dues from 194 member countries had dwindled to less than the budget of the New York City Department of Health. Starved of funds, the international system intended to control outbreaks like Ebola failed miserably in West Africa.

After that episode, the Obama administration established a White House–based directorate to respond to outbreaks and dedicated $1 billion to help poor countries build the basic capabilities to prevent, detect, and respond to pandemic threats. The Trump administration has assisted in the international response to Ebola in Congo and offered China help in the current coronavirus crisis, but it also dismantled the White House directorate on pandemic preparedness and urged that U.S. funding for global health security return to pre-2014 levels.

Humanity’s progress against infectious diseases is neither free nor irreversible. Tedros Adhanom Ghebreyesus, the director general of the World Health Organization, has requested $675 million to prepare poorer countries with weak health systems in case China cannot contain the newest coronavirus. “Our message to the international community,” Ghebreyesus said, “is invest today—or pay more later.”

The former is obviously the correct option. If the latest outbreak spreads to poorer nations in Africa or South America, it will become a pandemic, difficult for even the most prepared nations to control. This particular outbreak may have been hard to predict in advance, but the threat that a novel virus would pose to fast-urbanizing nations with underdeveloped health systems was not. Only investment in health-care systems, responsive governance, and the international architecture needed to prevent, detect, and respond to future outbreaks can prepare the world for threats like COVID-19. The historic improvements in global health over the last several decades are an opportunity, not a guarantee.

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