Two Texans and one Virginian were passengers on the cruise infested with a fatal hantavirus outbreak and returned to the country before it was identified, according to state health authorities.
Both passengers from the Lone Star State have no symptoms and did not have contact with anyone who was sick on the MV Hondius, the Texas Department of State Health Services said Thursday.
They have 'agreed to monitor themselves for symptoms with daily temperature checks,' according to a release.
The passengers will contact public health officials 'at any sign of a possible illness,' authorities added.
So far, three cruise ship passengers have died in the outbreak, and several others are sick. As of Wednesday, American officials were monitoring residents in three other states - Arizona, California and Georgia - for potential hantavirus infections.
A 70-year-old Dutch man was the first person to die on April 11 after experiencing days of severe illness.
Hantavirus symptoms typically show between one and eight weeks after exposure.
The Argentine government's leading hypothesis is that a Dutch couple who died had contracted hantavirus during a bird-watching outing at a garbage dump in Ushuaia, Argentina - where the MV Hondius departed from on April 1.
The MV Hondius cruise ship anchored in Praia, Cape Verde, on Monday
The Argentine government's leading hypothesis is that a Dutch couple who died contracted hantavirus while bird-watching at a garbage dump in Ushuaia, Argentina (File photo of a site in the city)
Texas authorities said contracting the hantavirus typically required 'close, prolonged contact with a person who is actively sick with the disease.'
'It is not known to spread through casual contact such as shaking hands or being in the same room for a few minutes,' the release added. 'There have been no documented cases where someone without symptoms spread it to someone else.'
The Virginia Department of Health also said it was monitoring a traveler from the cruise ship that had returned home, according to 13 News Now.
As of Thursday, the traveler was in good health and not showing any signs of infection.
Six Americans disembarked MV Hondius on April 24 on the island of St Helena, 13 days following the first death on board, operator Oceanwide Expeditions revealed on Thursday.
The CDC said Wednesday night that both it and the State Department were closely monitoring the status of US passengers.
'The Department of State is leading a coordinated, whole-of-government response including direct contact with passengers, diplomatic coordination, and engagement with domestic and international health authorities,' the CDC said.
It was revealed Thursday that six Americans had disembarked MV Hondius (picured) on April 24 on the island of St Helena
Officials have confirmed that two people in Georgia, one person in Arizona and an unspecified number of people in California were being monitored.
The Georgia Department of Public Health confirmed the agency was monitoring two residents but did not say where in the state the individuals are located or how long they will remain under monitoring.
Oceanwide Expeditions, the Netherlands-based cruise ship company, said Thursday that 30 passengers left the vessel at St. Helena.
The company had not previously revealed publicly that dozens more people left the ship.
The first hantavirus case on board of the vessel was not confirmed by authorities until May 2.
The body of the Dutch man who was the first to die on board on April 11 was taken off the ship on the remote South Atlantic island of St. Helena on April 24.
In a video, the ship's captain, Jan Dobrogowski, could be seen telling passengers that the death was because of 'natural causes.'
'Tragic as it is, it was due to natural causes, we believe,' Dobrogowski said. 'And also whatever health issues he was struggling with, I’m told by the doctor, were not infectious, so the ship is safe when it comes to that.
'The ship is safe. This gentleman, unfortunately, succumbed to natural causes. And like I say, we do what we can in order to continue in a safe and dignified way.'
The Dutch man's wife also disembarked, flew to South Africa a day later and died there.
On Thursday, the Netherlands' health ministry said a flight attendant on a plane briefly boarded by the woman was showing symptoms of hantavirus.
She would be tested in an isolation ward at a hospital in Amsterdam. If positive, the flight attendant could become the first known person not on the cruise ship to become infected.
This is a breaking news story. More to come.