Three people - a Dutch couple and a German national - died in the outbreak on MV Hondius.
Eight people, including a Swiss citizen, are suspected to have contracted the virus, according to the World Health Organisation.
The Dutch government on Wednesday said about 40 passengers had disembarked the ship in Santa Helena, including one of four Australians on board, according to media reports, when the ship made a stop on its way to Cape Verde - before the outbreak was reported.
The whereabouts of many of these passengers is as yet unknown.
One of those to disembark was the wife of the Dutchman who had died aboard the ship on April 11.
She fell sick herself and died before she could reach the Netherlands.
Dutch airline KLM on Wednesday said it had taken the woman off a plane in Johannesburg on April 25 due to her deteriorating medical condition.
The virus found in the victims has been confirmed as the Andean strain, which can spread among humans through very close contact.
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 on Wednesday it was closely monitoring the situation with US travellers on board the ship, adding that the risk to the American public was extremely low at the time.
French Foreign Minister Jean-Noel Barrot on Thursday said one French citizen had been in contact with a person who had fallen ill but was not currently showing symptoms.
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.
MV Hondius, with nearly 150 people on board, is expected to dock in Spain's Tenerife, in the Canary Islands, by Saturday.
Once in Tenerife, if they are still healthy, all non-Spanish citizens will be repatriated to their countries, while 14 Spanish passengers will be quarantined in a military hospital in Madrid.
Three patients were evacuated from the ship on Wednesday.
One of them has been admitted to a hospital in the Netherlands, while another one was transferred to Germany for medical care.
The plane carrying the third patient was set to land in the Netherlands early on Thursday after facing a delay due to a problem with the patient's life support system.
