Countries worldwide on Thursday scrambled to prevent further spread of the hantavirus, after an outbreak on a cruise ship, by tracking those who had already disembarked before the virus was detected and anyone in close contact with them since.
Three people - a Dutch couple and a German national - died in the outbreak on the Hondius. Eight people, including a Swiss citizen, are suspected to have contracted the virus, which is usually spread by rodents but can in rare cases be transmitted among people, the World Health Organisation said.
All passengers who disembarked in St. Helena in the South Atlantic Ocean, where the ship made a stop on April 24, have been contacted, the ship's operator said, adding this included people from at least 12 countries, among them seven British citizens and six from the US. The first confirmed case of hantavirus came in early May.
Experts have stressed that contagion is very rare, but the outbreak has put health authorities on high alert. The United States' Centers for Disease Control and Prevention (CDC) said it was closely monitoring the situation, adding that the risk to the American public was extremely low at the time.
The Georgia Department of Public Health said it was monitoring two asymptomatic residents who had returned home after disembarking from the cruise ship.
The Arizona Department of Health Services said in a separate emailed statement it was monitoring one resident, who was a passenger on the ship, and not symptomatic. According to the New York Times, California is monitoring an undisclosed number of residents who had also been on the ship.
One French citizen has been in contact with a person who had fallen ill but was not showing symptoms, Foreign Minister Jean-Noel Barrot said.
Oceanwide Expeditions said they were now working to establish details of all passengers and crew who embarked and disembarked on various stops since March 20. The Dutch couple who have died, and who are believed to be the first hantavirus cases of this outbreak, only boarded on April 1.
Dutch airline KLM on Wednesday said it had taken the Dutch woman off a plane in Johannesburg on April 25 due to her deteriorating medical condition. She died before she could reach the Netherlands.
According to broadcaster RTL, a KLM stewardess who had been in contact with her has now been admitted to a hospital in Amsterdam after showing possible hantavirus symptoms. The Dutch health ministry did not confirm that the woman being tested is a KLM stewardess, and neither did the airline.
But crew and passengers who helped the Dutch woman who passed away are being called daily for health checks, Dutch authorities told public broadcaster NOS.
The virus found in the victims has been confirmed as the Andean strain, which can, in rare cases, spread among humans through very close contact.
Argentina's health ministry has said it will carry out rodent trapping and analysis in the southern city of Ushuaia, the origin point of the cruise ship.
Three patients were evacuated from the ship on Wednesday. Two have been admitted to a hospital in the Netherlands, while another one was transferred to Germany for medical care.
Martin Anstee, an expedition guide, was one of the two in hospital in the Netherlands, according to Sky News, and told them he was "doing okay" but, "there are still lots of tests to be done."
The Duesseldorf University Clinic, treating the German evacuee, said she was not a confirmed case but rather a contact and was undergoing tests.
The plane carrying the third patient landed in the Netherlands on Thursday morning, and they were taken to a hospital in Nijmegen, in the east of the country.
In Switzerland, a person admitted to hospital on Monday was stable but showed symptoms consistent with a hantavirus infection, including low fever, body aches and a cough, the hospital said.
A Danish citizen who was aboard the Hondius has returned home and has been advised to self-isolate as a precaution, Danish health authorities said. The person is assessed to be at low risk, having had no close contact with those who later fell ill.
The Hondius, with dozens still on board, left its position off Cape Verde on Wednesday, where it had been marooned for days, and is expected to dock in Spain's Tenerife, in the Canary Islands, on Sunday, the EU's Centre for Disease Prevention and Control (ECDC) said.
There is still no one showing any hantavirus symptoms on the ship, the ECDC said.
Once in Tenerife, if they are still healthy, all non-Spanish citizens are set to be repatriated to their countries, while 14 Spanish passengers will be quarantined in a military hospital in Madrid.
(Additional reporting by Madeline Chambers in Berlin, Toby Sterling and Stephanie van den Berg in Amsterdam, John Revill in Zurich; Writing by Ingrid Melander; Editing by Alexandra Hudson)