“Our fear is that if we don’t die of the virus,” said Ms. García, 68, “we will die of hunger.”

The global spread of the new coronavirus has put millions of Indigenous people on high alert, aware that just a few cases could spell disaster in places far from hospitals or with little access to soap and water.

But along with concern about future infections are concerns about tonight’s dinner, or tomorrow’s lunch. Many Native communities are unprepared for months of economic paralysis. And in the worst cases, isolation measures are already causing emergencies.

“The little food we had left is gone,” said Adolfo Jusayú, 55, a father of four young boys.

Last week, with his income as a taxi driver halted by Colombia’s countrywide quarantine, all he could give his boys for the day was a drink made of cornmeal called chicha and a single arepa each.

Across the Americas, diseases brought in by outsiders once erased or devastated many Native nations, and this legacy remains strong in collective memories. In recent decades, diseases like measles and swine flu have wreaked havoc on some communities.

Already, more than a dozen Indigenous groups have reported cases of Covid-19, including the Yukpa in northern Colombia, the Six Nations of the Grand River Territory in southeastern Canada and the Navajo in the southwestern United States.