“To think that it is not in refugee and displaced populations is a bit naïve,” Mr. Coutts said.

If the virus is present, the camps are profoundly ill-equipped to handle it.

Many camp clinics are already struggling to fight outbreaks like dengue and cholera, leaving them without the resources to treat chronic conditions, such as diabetes or heart disease. The coronavirus, which has no vaccine or agreed upon treatment regimen for Covid-19, the respiratory disease it causes, could be even more devastating, medical experts warn.

“We are preparing for the worst,” said Avril Benoit, the executive director of Doctors Without Borders in the United States, which has deployed teams to work with refugees around the world. “We know that in the places where we work we are underequipped and understaffed.”

Daily life in a refugee camp is an ideal incubator for infectious disease. Many lack running water and indoor sanitation. People often stand in line for hours to get water, which is insufficient for frequent showers, much less vigilant hand washing.

“If it came into the camp, it would be a disaster,” said Ahmadu Yusuf, a community leader in the Bakassi camp in northeastern Nigeria, most of whose residents fled Boko Haram, the militant group. “It would be more devastating than the insurgency that brought them here.”

Refugee life also makes social distancing, the health mantra in the West, impossible.

In crowded, poor places like Gaza or the urban slums of Indonesia and India, which began the world’s largest lockdown in response to the virus this week, keeping six feet away from everyone else is difficult. Refugee settlements are often even denser.

A refugee camp in Lesbos, Greece, was built for 3,000 people but now has 20,000 and almost no sanitation.