The first plane carrying passengers evacuated from a cruise ship hit by a deadly hantavirus outbreak has taken off from Tenerife and is bound for the Spanish mainland.

The MV Hondius arrived off the coast of Tenerife, one of Spain’s Canary Islands, early Sunday morning local time.

Those on board are being transferred by smaller boats to the Port of Granadilla, then taken in sealed-off buses to the airport for repatriation flights. Spanish nationals are being evacuated first, with other nationalities to follow in groups.

Six people have now been confirmed as infected with hantavirus, and four are hospitalized, according to the World Health Organization (WHO). Three people have died: a Dutch couple and a German national.

Health authorities from a dozen countries, including the U.S., are scrambling to track down and monitor passengers who disembarked on April 24 on the island of St. Helena, a British overseas territory in the South Atlantic, without contact tracing, nearly two weeks after the first passenger died on board.

Health officials in Arizona, California, Georgia, New Jersey, Texas and Virginia are monitoring residents for potential infections linked to the cruise ship. New Jersey was the latest state to announce it was tracking residents. No U.S. cases have been reported.

The U.S. Centers for Disease Control and Prevention issued a Health Alert Network advisory on Friday, alerting doctors and state health departments to be aware of potential imported hantavirus cases, ABC News reported. The CDC has classified the outbreak as a Level 3 emergency response, the lowest level of emergency activation, and has deployed teams to the Canary Islands and to Offutt Air Force Base in Nebraska, where the 17 American passengers will be taken to the National Quarantine Center at the University of Nebraska after they are repatriated.

WHO Director-General Tedros Adhanom Ghebreyesus said Saturday that the leading theory explaining how the virus reached the ship could be traced back to the first two cases — a Dutch couple — who had traveled through Argentina, Chile and Uruguay on a birdwatching trip “which included visits to sites where the species of rat known to carry the virus was present,” according to the Telegraph.

Maria Van Kerkhove, an infectious disease epidemiologist at the WHO, urged people not to panic, saying at a Thursday press briefing: “This is not COVID, this is not influenza; it spreads very, very differently.”

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