The mood inside the National Quarantine Unit was electric with despair and fury.

It was May 17, six days after United States health officials had evacuated 18 Americans from the cruise ship at the center of a hantavirus outbreak that had killed three people, and taken them to the special facility in Omaha, Neb., for what they had said would be a quick 72-hour evaluation before the passengers could go home to quarantine.

None of them had tested positive for the virus but now, an official from the Centers for Disease Control and Prevention, Dr. David Fitter, was telling them on a video call that they would not be permitted to leave for at least two more weeks.

These were people who had paid thousands of dollars for a cruise through uninhabited regions, in pursuit of exotic birds and animals. They chafed against the loss of fresh air, nature and, most of all, their freedom.

“I’m asking you, as a scientist and a human,” a passenger with a red-headed woodpecker as his Zoom icon said to Dr. Fitter, on a copy of the video call viewed by The New York Times. “Do you think that this is really a sensible decision to keep me here in this room that’s making me sicker day by day, being here when I could be home isolating in a perfectly reasonable situation?”

Looking distinctly uncomfortable, Dr. Fitter responded: “I think that the best that I have for you right now is that I will pass this up.”

News of the outbreak aboard a cruise ship, with its echoes of the early days of the Covid pandemic, alarmed people around the world. The little-studied Andes hantavirus has a mortality of nearly 40 percent among hospitalized patients, prompting countries to evacuate their citizens from the ship and monitor them for 42 days, the incubation period for the virus. Some were initially held in official facilities. But American health officials had the strictest rules over the long term, holding people in the quarantine unit despite recommendations from C.D.C. scientists that they be allowed to self-monitor at home.