What we don't know about the hantavirus outbreak as the cruise ship nears Spanish territory

THE HAGUE, Netherlands (AP) — Countries around the world are preparing to deal with the 140 passengers and crew members on board a hantavirus-stricken cruise ship headed for the Canary Islands.

The vessel is expected to reach the Spanish island of Tenerife, off the coast of West Africa, early Sunday morning.

At least three passengers have died, and several other people have been infected.

Hantavirus is usually spread by the inhalation of contaminated rodent droppings. Symptoms usually show between one and eight weeks after exposure. The World Health Organization says the risk to the wider public from the outbreak is low, but the Andes virus implicated in the cruise ship outbreak may be able to spread between people in rare cases.

Authorities and the cruise operator have been providing updates, but some key information is still lacking.

Here's what we don't know:

Where the outbreak originated

Argentine investigators suspect a Dutch couple may have first contracted the virus while on a bird-watching trip before they boarded the cruise ship in Argentina on April 1. But no organization has confirmed where or how they acquired the disease.

Argentina’s Health Ministry has zeroed in on the nation's southernmost town, Ushuaia. Officials plan to travel there in the coming days according to a written statement to The Associated Press. No explanation was given for the delay.

What happens next to the remaining passengers

Spanish authorities are preparing to receive the remaining passengers and crew members on Tenerife. Officials said Friday that once the ship reaches Tenerife, passengers will be evacuated in small boats to buses only once their repatriation flights are ready to take them.

The United States has agreed to send a plane to the Canary Islands to pick up its citizens, as will the British government. Other countries have not yet made their plans public and it is not clear for how long passengers on the boat will have to wait for their flights.

Virginia Barcones, Spain’s head of emergency services, said on Friday the country had requested medically equipped planes for passengers experiencing symptoms but it wasn't known if those would be available.

How many people may have been exposed

According to cruise operator Oceanwide Expeditions, the MV Hondius departed Ushuaia on April 1 and made two stops before the outbreak occurred.

Six more passengers boarded at the remote island of Tristan da Cunha. The ship then made a stop at the island of St. Helena, where 30 passengers disembarked, including a Dutch woman and the body of her deceased husband. The nationalities of two of those 30 passengers are unknown. They are thought to be Chileans who boarded at Tristan da Cunha, according to the company.

Stephen Doughty, the U.K. minister of overseas territories, said on Friday that a resident of Tristan da Cunha has been hospitalized with symptoms of hantavirus. It is not clear if this person was a passenger on the ship.

Initial figures provided by Oceanwide Expeditions said the ship left Argentina with 114 passengers and an unknown number of crew members onboard. Later figures provided by Oceanwide Expeditions say the ship had 61 crew members from 12 countries, but it’s not known if any of the crew changed during the ship’s journey.

Oceanwide Expeditions was forced to update the number and nationalities of the passengers who disembarked on St. Helena after discovering a discrepancy in their initial figures. Their number is lower than the Dutch Foreign Ministry's estimate, and the reason for the difference is unknown.

The whereabouts of all of the passengers

Many of the passengers who disembarked at St. Helena traveled on to other countries, including the Dutch woman whose husband died on board. She flew to Johannesburg then briefly boarded a plane preparing to fly to Amsterdam. She was removed because she was too ill to travel, and later died.

South African and Dutch authorities are trying to trace the whereabouts of anyone who had contact with the deceased woman during her travels. A flight attendant, who had contact with the woman, has tested negative for hantavirus after reporting symptoms.

Some governments, like the United Kingdom, have confirmed the whereabouts of their citizens who left the boat. According to U.K health officials, two are self-isolating at home, four remain on St. Helena, and one “has been traced outside of the U.K..” However, U.K. officials do not know or have not made public how many others they have come into contact with since.