"Spain reported a new case among the passengers who are in quarantine, which brings the total number of cases to 13," WHO chief Tedros Adhanom Ghebreyesus said in a post on X on Wednesday.
It is the second positive case among the 14 Spanish nationals who were evacuated to the Spanish island of Tenerife from the MV Hondius.
The luxury liner had been carrying about 150 passengers and crew from 23 countries when a cluster of severe respiratory illnesses was first reported to the World Health Organisation on May 2.
Three people have died, but there have been no new deaths since May 2, Ghebreyesus said.
"The situation remains stable. Passengers who got sick are receiving needed care, while others remain in quarantine."
In the last two weeks all remaining passengers, crew members and medical staff disembarked the Hondius.
There is no specific therapy for hantavirus, which is primarily spread by rodents but can be transmitted between people in rare cases and after prolonged, close contact.
The WHO estimates there are 10,000 to 100,000 human cases globally each year, with severity varying by strain.
