Health officials are scrambling to track the hantavirus outbreak on cruise ships but are predicting “limited” spread

Health authorities in a growing list of countries scrambled Thursday to track down people linked to a deadly hantavirus outbreak on a cruise ship. The World Health Organization also predicted “limited” spread of the virus if public health measures were implemented.

“This is not Covid, this is not influenza,” said Dr. Maria Van Kerkhove, head of the WHO’s Epidemic and Pandemic Preparedness Department, at a press conference in Geneva on Thursday. “It spreads very, very differently.”

Person-to-person transmission of hantavirus, a family of viruses transmitted by rodents, is rare. The Andean strain of hantavirus, which has been confirmed in cases linked to the cruise ship, is the only one known to transmit from person to person, but it is primarily transmitted through close personal contact, Dr. Van Kerkhove.

“This is not the start of an epidemic, this is not the start of a pandemic,” she said.

Since April 11, three passengers aboard the MV Hondius, a Dutch-flagged cruise ship, have died and at least five other people have fallen ill after showing symptoms of hantavirus, the WHO said. Health authorities have confirmed five cases of hantavirus on the ship so far, all of which are of the Andean strain, which is found primarily in South America.

In several countries, people are now being tested or monitored after they may have come into contact with the virus.

Three people in the Netherlands who developed symptoms after coming into contact with an infected person on a plane have been tested for the virus, Dutch health authorities said. Two of the results were negative and the third was still being analyzed.

Earlier, the Dutch Health Ministry said a flight attendant underwent a test for hantavirus at a hospital on Thursday after coming into contact with an infected person.

Dutch media reported that the flight attendant worked for KLM Royal Dutch Airlines. The company declined to comment, citing concerns about its employees’ privacy. The Dutch Ministry of Health did not say whether the two negative results also affected the flight attendant.

Authorities did not say whether the flight attendant was showing symptoms or whether she had worked on a flight that one of the victims of the cruise ship outbreak had briefly boarded the day before his death. The victim, a 69-year-old Dutch woman, died on April 26 in Johannesburg, South Africa.

The day before her death, the woman boarded KLM Flight 592 from Johannesburg to Amsterdam and spent about an hour on the plane, according to the airline. Barbara de Beukelaar, a passenger on that flight, said in a telephone interview that the woman in a wheelchair was helped onto the plane.

According to KLM, airline employees attended to the woman and decided to remove her from the plane before the nearly 12-hour flight departed because of her condition.

“Nobody on board believed they were dealing with a contagious virus,” Ms de Beukelaar said.

KLM said it had handed over the flight’s passenger list to Dutch health authorities for contact tracing.

Do you have a confidential news tip? The New York Times would like to hear from readers who would like to share messages and materials with our journalists.

The Hondius – carrying nearly 150 passengers and crew from nearly two dozen countries – was en route to the Canary Islands on Thursday after three people possibly infected with the virus were evacuated to the Netherlands.

The ship will not dock in the Canary Islands, but will remain anchored off the coast until the passengers are taken by boat to Tenerife for evacuation flights to their countries, the Canary Islands authorities said. The ship is scheduled to arrive there on Sunday.

Oceanwide Expeditions, the Dutch company operating the cruise, said in a statement Thursday that two of the people evacuated to the Netherlands were crew members with symptoms, a 56-year-old British citizen and a 41-year-old Dutch citizen.

A 65-year-old German woman without symptoms was also evacuated. According to the University Hospital Düsseldorf, she is currently undergoing tests in Germany.

Dr. Jeanne Marrazzo, the head of the Infectious Disease Society of America, told reporters Thursday that “our concern should be very high” but urged people not to panic.

“It’s not a situation where there’s going to be an outbreak all over the world, all over the world, probably because of these kinds of small cases of inflammation,” she said. “We don’t know yet, but we really have to try to stay calm and focus on the context and consider the risk in these situations.”

Genetic sequencing of samples in South Africa suggests that the virus is nearly identical to the version seen in Argentina and has not mutated in a way that would make it a major threat, according to Tulio de Oliveira, director of the Center for Epidemic Response and Innovation at Stellenbosch University in South Africa. Dr. De Oliveira was not involved in the work but said the results were presented To a group of experts to which he belongs.

It could prove difficult to trace everyone who may have come into contact with those suffering from the virus.

On April 24, 30 people from at least 12 different countries disembarked in St. Helena, a remote island in the South Atlantic. According to Oceanwide, that was more than a week before the first confirmed case of the virus was reported.

The company said it had contacted the people who disembarked in St. Helena. According to the WHO, at least one of them, a man from Switzerland, was treated in a hospital in Zurich and tested positive for the virus

“We are working to determine details of all passengers and crew who have boarded and disembarked the ship since March 20,” Oceanwide said.

According to the National Center for Infectious Diseases, two people who were on the ship were in isolation in Singapore and were being tested for the virus. In Denmark, local health authorities said a Danish passenger on the ship who had not been tested for hantavirus was self-isolating and showing no symptoms.

A French citizen who came into contact with one of the cruise passengers on a flight from the island of St. Helena to Johannesburg on April 25 showed mild symptoms and is in isolation, French officials said on Thursday. That person will also undergo diagnostic testing, officials said. Seven other French nationals on the flight are being monitored.

In the United States, residents in five states were monitored for possible hantavirus infections after their stay on the ship, officials said. None of them had symptoms, officials said.

Reporting was written by Lynsey Chutel in London, Apoorva Mandavilli in New York City, Carlos Barragán in Tenerife, Spain and Amelia Dürrenberg in Copenhagen, Denmark.