“You want us to wash our hands?” asked Fadi Mesaher, the Idlib director for the Maram Foundation for Relief and Development. “Some people can’t wash their kids for a week. They are living outdoors.”

Syrian doctors believe the virus has already swept into the camps, with deaths and illness that bear the hallmarks of the outbreak. But the international response has been slow to nonexistent, according to more than a dozen experts and Syrian medical professionals.

The World Health Organization has not yet delivered coronavirus testing kits to the opposition-held northwest, despite making its first delivery of such kits to the Syrian government more than a month ago.

Doctors said the delay has probably allowed the virus to spread undetected for weeks in a uniquely dangerous environment.

“We currently have cases that are similar, and we’ve had people die,” said Dr. Mohamed Ghaleb Tennari, who manages the Syrian American Medical Society’s hospitals in the region. “But unfortunately because we don’t have the test, we can’t confirm that these cases are truly corona or not.”