A French woman with hantavirus who had traveled on the MV Hondius cruise ship was critically ill on Wednesday, officials said, as the number of identified cases in the outbreak climbed to 11.
Health officials around the world are monitoring disembarked travelers from the ship and any of their close contacts for symptoms of the virus. The World Health Organization said on Tuesday that nine people had been confirmed to have the hantavirus, three of whom had died. It described two further patients as “probable” cases.
Officials at a briefing on Wednesday in Stockholm by the European Center for Disease Prevention and Control said that the patient in France was one of three people to be critically ill. Gianfranco Spiteri, an epidemic expert at the agency, said the woman did not have symptoms when she left the ship.
Xavier Lescure, an infectious disease specialist at Bichat Hospital in Paris, where the woman is being treated, had previously said the she had severe symptoms and was breathing with the help of an artificial lung.
Pamela Rendi-Wagner, the agency’s director, noted that the virus had a long incubation period of six weeks. She recommended that the ship’s passengers be held in quarantine for that length of time after disembarking.
The W.H.O. has said that its officials expect to see more hantavirus cases “given the dynamics of spread on a ship” and the long incubation period, even as the risk of a larger outbreak remains low.
All of the cases identified so far have been among the 150 passengers and crew aboard the MV Hondius, a Dutch-registered cruise ship that was in the South Atlantic when an outbreak began on board.
Health authorities have been identifying people to have close contact with the passengers and asking them to quarantine too.
On Tuesday, a hospital in the Netherlands said 12 of its employees could have been exposed to the virus while processing blood and urine samples from an infected patient. It said that they would enter preventive quarantine for six weeks as a precaution.
The MV Hondius departed for an Atlantic adventure cruise from Argentina last month. Within days, a 70-year-old Dutch man developed symptoms. He died onboard the ship on April 11 and his 69-year-old wife became ill and died on April 26 in Johannesburg, South Africa, while attempting to fly home to the Netherlands. On May 2, a German woman also died aboard the ship after developing flu-like symptoms. The W.H.O. said her body later tested positive for the virus.
Hantavirus is a rare family of viruses carried by rodents. The outbreak on the ship involved the Andes subtype, the only type known to spread among humans. It affects those who are in prolonged, close contact with someone with the virus. Early symptoms can resemble those of flu, but as the illness progresses it can cause shortness of breath and, in severe instances, lung or heart failure.
The W.H.O. believes that the Dutch couple had been infected with the virus before boarding the ship.
The MV Hondius anchored off Spain’s Canary Islands on Sunday and passengers and crew began evacuating to their home countries for quarantine and monitoring. Spanish authorities said 32 crew members will remain on the ship until it docks in the Netherlands.
In the United States, 18 Americans from the cruise ship are being monitored at medical facilities in Nebraska and Georgia. On Tuesday, the Department for Health and Human Services said that one member of a couple who was sent to a hospital in Atlanta with mild symptoms had tested negative for the Andes strain of hantavirus.
It said that the 16 others who had been transferred from the cruise ship to a medical facility in Omaha remained asymptomatic, including one person who had tested “mildly” positive for the virus.
