News over the weekend that an 83-year-old American woman who was on the ship and flew from Cambodia to Malaysia was found to be carrying the virus froze further movement of the passengers and crew of the Westerdam. Some are in hotels in Cambodia's capital, Phnom Penh, while others are still aboard the ship.

The American woman was among several hundred passengers who were flown out of Cambodia on Friday and Saturday. According to authorities in Malaysia, 143 continued their flights home from that country, while the woman and her 84-year-old husband, who was diagnosed with pneumonia, remained behind for treatment.

The dispersal around the world of passengers from the ship with possible exposure to the new coronavirus has sparked concern.

"I think now given that there is a confirmed case that is suspected to have acquired infection on board the ship, the other passengers should be asked to quarantine themselves at home and alert health authorities if they develop fever or respiratory symptoms within the 14 days since disembarkation," said Professor Benjamin Cowling from the School of Public Health at Hong Kong University.

Dr. Gagandeep Kang, executive director of India's Translational Health Science and Technology Institute, said it is unclear whether the woman's infection would result in an outbreak in another part of the world. The virus that causes the disease named COVID-19 has been confirmed in about two dozen countries, with most cases concentrated in China, where it emerged in December.

"We will have to wait and see," she said, adding that it would depend on where the woman got the infection, and at what stage of the infection she was in while in contact with other people.

The ship's operator, Holland America Line, said in a statement Monday that Cambodian health officials were on the ship testing the 255 guests and 747 crew who were awaiting clearance, and that guests currently staying at a Phnom Penh hotel had all been tested.

"At this time, no other guests or crew on board or at the hotel have reported any symptoms of the illness. Guests who have already returned home will be contacted by their local health department and provided further information," it said.

The statement added that the virus patient had not reported any illness to the Westerdam's medical center during the cruise. Twenty people who reported illness while on board have tested negative for the virus, it said.

The rest of the passengers and crew had health checks that included filling out a written health questionnaire and having their temperatures checked, which has become standard procedure for air and sea passengers considered at risk.

Several Westerdam passengers from the United States and elsewhere have already returned home and spoken to the media.

Two of the passengers, Joseph Schaeffer and his wife, Paulette, a retired nurse, told the Las Vegas Review-Journal from their home in Henderson, Nevada, that they felt the hue and cry over the released passengers was not totally merited.

"It doesn't seem to me that the whole world should be jumping at this," Joseph Schaeffer said.

"There are more deaths from the flu than there have been from this particular virus," his wife said.

The couple said they were screened on their way home at airports in Phnom Penh and Singapore by thermal scanners that remotely monitor arriving passengers.

On arrival in Los Angeles, they said, they were among a large crowd getting screened that included fellow cruise passengers. They said they answered questions gfrom the Centers for Disease Control and Prevention that included whether they felt sick, had visited mainland China or knew anyone who had contracted the virus.

Two Canadians who returned via Vancouver International Airport were asked to put on protective face masks on arrival but were not otherwise isolated, Canada's CBC News reported.

"We were asked a few questions and filled out an immigration form, and they very nicely helped us bypass the usual lineups and let us out the door," said Joseph Hansen, who took the cruise with his wife. "We're feeling fine."

Hansen, from Surrey, British Columbia, told CBC that he did not hear about the American woman in Malaysia with the virus until he landed in Vancouver on Sunday.

"I guess on the one hand it's upsetting to know that there was one case, but we're feeling fine," he said. "We've had health scans, temperature scans and we don't have any concerns for our own health."

Cambodia's government had originally earned kudos from the head of the U.N.'s World Health Organization and the U.S. ambassador there for allowing the ship to dock at Sihanoukville after it was turned away by Japan, Taiwan, the Philippines, Guam and Thailand.

The move was seen as a victory for the image of Cambodia's authoritarian leader, who welcomed the ship's passengers with handshakes and flowers. Prime Minister Hun Sen boasted that although Cambodia is a poor country, it "has always joined the international community to solve the problems that the world and our region are facing."

WHO Director-General Tedros Adhanom Ghebreyesus had said he was pleased Cambodia had agreed to accept the Westerdam and described it as an example of the international solidarity advocated by the U.N. health agency.

"The one thing I can say is we're very, very grateful that Cambodia has opened literally its ports and its doors to people in need," U.S. Ambassador to Cambodia W. Patrick Murphy said Saturday when he took his family to the port to meet passengers. "We think this sends a strong message. We all have to help each other."

In hindsight, however, Cambodia's handling of the ship's passengers has been criticized on social media, though it also has gotten some support.

According to Cowling, the Hong Kong University professor, it's a good idea to let passengers leave and monitor them after disembarkation.

Since there were no known cases on board the Westerdam at the time passengers left the ship, it was reasonable to allow them to travel home, he said.

"I think it would not be appropriate to keep passengers on the ship for 14 days, as it could be a high-risk environment," Cowling said.

"We have seen the consequences of holding passengers on a cruise ship with the Diamond Princess outbreak," he said, referring to another cruise ship that is quarantined in Yokohama, Japan, with hundreds of cases among the passengers.