BAD AS it has been, the damage the covid-19 epidemic is inflicting on the United States and Europe could soon be overtaken by catastrophes in poorer and more distressed parts of the world. In areas of Africa, the Middle East and Latin America, escaping the new coronavirus through social distancing or even hand-washing will not be an option — and obtaining treatment from health-care services will be next to impossible. The result could be staggering death tolls, major social disruptions and new waves of refugees headed for the United States and Europe.

The virus has been slower to arrive in countries south of the Mediterranean and Caribbean seas, but hopes that it would not spread in warmer countries haven’t been borne out. The first cases were reported this week in the Gaza Strip, where nearly 2 million Palestinians are crammed into an area only twice the size of the District of Columbia, and where hospitals normally maintain only 40 intensive care beds. Several dozen more cases have been recorded in the nearby West Bank. Cases also have been reported in perpetually war-ravaged Somalia and Congo.

Aid workers worry even more about the sprawling refugee camps that now contain millions of people around the world, including the 1 million Rohingya who fled Myanmar for neighboring Bangladesh. In the northwestern Syrian province of Idlib are more than 1 million people who have been driven from their homes in recent months by Russian and Syrian government bombing, much of which has been deliberately aimed at hospitals. In northeastern Syria, the al-Hol camp contains 70,000 people, most of them women and children who fled the Islamic State and who lack adequate food and water, not to mention medical services.

“These are places where people who have been forced to flee their homes because of bombs, violence or floods are living under plastic sheets in fields or crammed into refugee camps or informal settlements,” U.N. Secretary General António Guterres said Wednesday. “They do not have homes in which to socially distance or self-isolate. They lack clean water and soap with which to do that most basic act of self-protection against the virus — washing their hands. And should they become critically ill, they have no way of accessing a health care system that can provide a hospital bed and a ventilator.”

Preoccupied with fighting the virus at home, the United States and other rich nations have done little to head off these potential covid-19 disaster zones. But as Mr. Guterres pointed out, doing so is not only a moral imperative; it is also crucial to ending the pandemic. Without action, he said, “the virus will establish a foothold in the most fragile countries, leaving the whole world vulnerable as it continues to circle the planet.” Inevitably, too, an uncontrolled outbreak in these areas will propel new waves of desperate refugees northward.

Mr. Guterres unveiled a response plan put together by the World Health Organization and U.N. humanitarian agencies as well as nongovernment groups. The $2 billion in funding they are seeking would provide tests, supplies for medical workers, and water and sanitation to places that now lack it. The requested resources, the secretary general pointed out, are a drop in the bucket compared with what Western governments are spending on their own citizens. But they are critical to defeating the disease.

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