An asylum seeker has tested positive for coronavirus in a sprawling encampment steps from the U.S. border in Matamoros, Mexico, underscoring the challenges migrants face in protecting themselves from the pandemic.

After showing symptoms of the virus last Thursday, the migrant and three family members were placed in isolation and tested, Global Response Management (GRM), a nonprofit providing medical services in the camp, said in a statement.

When results came back Monday, the migrant who had displayed symptoms tested positive and the relatives had negative results.

Two others with symptoms of the virus are also in isolation, GRM said.

Since cases of coronavirus in Mexico began to rise in March, advocates and government officials have been intensely worried about the potential for an outbreak in the camp, where an estimated 2,000 migrants live in tents on the banks of the Rio Grande river.

“The presence of COVID-19 in an already vulnerable population exposed to the elements could potentially be catastrophic,” GRM said in a statement.

U.S. Customs and Border Protection did not immediately respond to a request for comment.

Many migrants living in the camp are U.S. asylum seekers who were sent back to Mexico to await the outcome of their cases under a controversial Trump administration policy known as “Migrant Protection Protocols.”

To prepare for the virus, GRM sought to improve sanitation in the camp by setting up 88 “handwashing stations,” distributed multivitamins to boost migrants’ immune systems and built a 20-bed field hospital.

Luz, a 42-year-old asylum seeker from Peru who asked that her last name not be used due to safety concerns, said she has tried to isolate as much as possible, though she sometimes ventures out of her tent to seek some relief from the fierce Matamoros heat.

“I truly am not afraid, though I try to be cautious,” she said. “But you can’t stay in your tent all the time… It’s too hot.”

Reuters