A person who was among five French nationals aboard the MV Hondius has shown signs of hantavirus infection, according to the French prime minister.

"Five of our compatriots present on the MV Hondius, a hotbed of Hantavirus infection, have been repatriated to national territory. One of them exhibited symptoms on the repatriation flight," Prime Minister Sebastien Lecornu posted Sunday on X.

"As a result, these five passengers were immediately placed in strict isolation until further notice," Lecornu said, adding that the passengers "are receiving medical care and will undergo testing and a full health assessment."

"Starting this evening, I will issue a decree to implement appropriate isolation measures for close contacts and to protect the general population," Lecornu added.

If confirmed, the French national would bring to nine the total number of confirmed and probable cases of hantavirus onboard the ship, including two people confirmed to have died from the virus and one person who remains suspected to have died from the virus.

During his public noontime prayer Sunday in St. Peter's Square, Pope Leo thanked residents of the Canary Islands for their "hospitality" shown to the MV Hondius and its passengers.

"I would like to thank the people of the Canary Islands who, with the hospitality characteristic of them, welcomed the cruise ship Hondius and the passengers infected with the hantavirus," the pontiff said.

"I look forward to seeing all of you next month during my visit to the islands," the pope added, referring to the visit that had already been planned as part of a broader trip to Spain in June.

The passengers aboard the MV Hondius, including 17 Americans, disembarked from the ship Sunday in Tenerife, in the Canary Islands, to begin their journeys back to their home countries.

-ABC News' Phoebe Natanson

The hantavirus outbreak aboard the MV Hondius "is on the end of its run right now," a top infectious disease expert told ABC News "This Week" Sunday.

"The good news is that, in a sense, it is hantavirus and not another coronavirus or influenza virus. This is one that has very limited ability to be transmitted person to person. In fact, it's a rare exception," Dr. Michael Osterholm, director of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), told ABC News' Martha Raddatz. "And so we have no question about the fact that this really is on the end of its run right now."

There are about 30 cases of hantavirus a year in the U.S. on average, and "they mostly occur west of the Mississippi" – about 96%, Osterholm said, due to a specific mouse that lives in that region. He also said that person-to-person transmission of the hantavirus strain in question is "a very rare exception," and only occurs when someone is exhibiting symptoms of the virus.

"Right now, you can manage the individuals who have been exposed very simply by asking them twice a day, 'are you experiencing any kind of a fever?' And then take the temperature: 'Do you have any symptoms?' If somebody is identified right at that point, you can put basically an N95 mask on and stop all transmission," Osterholm said.

"So this is why we don't need this high-tech, you know, containment facilities, et cetera, to monitor these people. We can monitor them very simply," Osterholm added, explaining why quarantining returning Americans isn't necessary.

"I have complete confidence that we will have good compliance here," Osterholm said of monitoring passengers who are returning. "And I think within days, this will no longer be a story."

-ABC News' Quinn Scanlan

An airplane from the U.S. is expected to land in Tenerife, in the Canary Island, at 5:23 p.m. local time/12:23 p.m. Eastern time, according to a source in the Spanish president's office.

The aircraft will carry U.S. passengers only, according to the source. There are 17 U.S. citizens aboard the ship who will be returning to the United States.

As of now, the U.S. airplane is expected to take off from Tenerife at 9:30 p.m. local time/4:30 p.m. Eastern time but could possibly depart earlier if circumstances allow, the source said.

The passengers onboard the MV Hondius began disembarking from the ship in Tenerife on Sunday morning.

-ABC News' Aicha El Hammar

Two residents of King County, Washington, are being monitored at home after potentially being exposed to hantavirus, the Seattle and King County Public Health Department said.

The two residents sat on a plane near an ill passenger from the cruise ship; that passenger was removed from the plane and later tested positive, officials said.

The two residents don’t have symptoms and are being monitored, officials said.

"Currently, no one in King County has symptoms of hantavirus and there are no cases of the virus in King County," the health department said. "The risk to the public remains low."

A resident of King County is also among the cruise ship passengers now being monitored at the quarantine center in Nebraska, the officials added.