CHICAGO — Bedbugs.

The biting pests that infest hotels appear to be the source of red marks on a Minnesota woman that prompted health officials to quarantine a jet in Chicago for fear they were dealing with something much more serious: monkeypox.

On Friday, the woman’s son explained how one comment got misunderstood and one thing led to another until the situation began to resemble a scene from a science fiction movie.

Roger Sievers said the confusion began when his mother, 50-year-old Lise Sievers, called her mother during a layover in Detroit. Lise Sievers said one of the children she visited and is trying to adopt in Uganda had some pus-filled red bumps. And she mentioned she had some small bumps of her own, a rash that she suspected was the handiwork of bedbugs.

Those two very different bumps — one with pus, one without — got jumbled up in Siever’s mother’s mind, and she called a hospital near her Indiana home to ask about treatment for her daughter.

“She told them her daughter is on a flight back from Uganda and has some red bumps which are pussing and what should she do to treat them,” Roger Sievers said. “She was looking for some general advice.”

What she got was something else.

The hospital telephoned the federal Centers for Disease Control and Prevention, which didn’t like the sound of pus and Uganda in the same sentence. When the plane touched down at Midway International Airport in Chicago, the passengers looked out the window to see the jet surrounded by fire trucks, police cars and ambulances. Health officials came through the door wearing facemask and other protective gear.

“They came up and took some photos of my mom and sent them to Washington,” said Sievers, 29, of Red Wing, Minn.

Health officials feared they were looking for monkeypox, a rare and sometimes fatal disease mostly in found in central and western Africa.

But after the passengers waited on the plane for a couple of hours, officials brought good news, Roger Sievers said. “They came back down and told my mom it was bed bug bites and they started releasing people” from the jet.

Roger Sievers said his mother had been in Uganda since January because she is in the process of adopting two special-needs children there. She was returning to Minnesota to raise money for their travel to the United States and will return to Uganda in a month to complete the adoptions, he said.

Lise Sievers has adopted 10 other children from around the country and has two biological children.