The Dutch-flagged MV Hondius, with more than 140 passengers and crew on board, is headed to Spain's Canary Islands - off the coast of west Africa -and is expected to arrive at the island of Tenerife early on Sunday.
WHO director-general Tedros Adhanom Ghebreyesus along with Spanish Health Minister Monica Garcia and Interior Minister Fernando Grande-Marlaska were due on the island on Saturday to co-ordinate the disembarkation of passengers and some crew.
"I know you are worried. I know that when you hear the word 'outbreak' and watch a ship sail toward your shores, memories surface that none of us have fully put to rest. The pain of 2020 is still real, and I do not dismiss it for a single moment," Tedros said in a message to the people of Tenerife.
"But I need you to hear me clearly: This is not another COVID-19. The current public health risk from hantavirus remains low. My colleagues and I have said this unequivocally, and I will say it again to you now," Tedros added.
The WHO, Spanish authorities and cruise company Oceanwide Expeditions said nobody on the Hondius is currently showing symptoms of the virus.
Hantavirus can cause life-threatening illness.
It usually spreads when people inhale contaminated residue of rodent droppings and is not easily transmitted between people.
But the Andes virus detected in the cruise ship outbreak may be able to spread between people in rare cases.
Symptoms usually show between one and eight weeks after exposure.
Three people have died since the outbreak, and five passengers who left the ship are infected with hantavirus.
Some on Tenerife say they are worried.
On board the cruise ship, some Spanish passengers have voiced concern about being stigmatised.
"I tell you, I don't like this very much," 69-year-old resident Simon Vidal said.
"Anyone can say what they want. Why did they have to bring a boat from another country here? Why not anywhere else, why bring it to the Canary Islands?"
Spanish Health Minister Monica Garcia said passengers and some crew would disembark in Tenerife "under maximum safety conditions".
The ship will not dock but will remain at anchor.
Everyone disembarking will be checked for symptoms and will not be taken off the ship until a flight is already in Tenerife waiting to fly them off the island, Garcia said during a news conference in Madrid.
There are people of more than 20 different countries on board.
Both the United Kingdom and the United States have agreed to send planes to return their citizens.
UK passengers and staff will be taken to a hospital in northwest England for an initial isolation period once they are repatriated, UK health authorities said.
The ship, the MV Hondius, is expected to anchor off the Spanish island of Tenerife early on Sunday, following which the 22 UK citizens on board will be flown back.
US citizens are to be quarantined at a medical centre in Nebraska.
All Spanish passengers will be transferred to a medical facility and quarantined, Garcia said.
Oceanwide has listed 13 Spanish passengers and one Spanish crew member on board.
Those disembarking will leave behind their luggage, Garcia said, and will be allowed to take only a small bag with essential items, a phone, charger and documentation.
Some crew as well as the body of a passenger who died on board will remain on the ship, which will sail on to the Netherlands where it will undergo disinfection.
with Reuters
