Top WHO official warns cruise passengers are 'high-risk contacts' as Americans return from hantavirus ship

A World Health Organization (WHO) official is warning that passengers aboard a hantavirus-hit cruise ship should be treated as "high-risk contacts" as Americans return home following an outbreak that has left three people dead.

"Our recommendations are we're considering everyone on board, the crew and the passengers as high-risk contacts because there are current investigations that are really trying to understand what types of exposures each of them had," said Maria Van Kerkhove, acting director of the Department of Epidemic and Pandemic Threat Management at WHO.

"Because there's so much uncertainty at the moment, we've recommended that everybody be considered a high-risk contact."

Kerkhove told Fox News' Jacqui Heinrich during "The Sunday Briefing" that the organization is requiring a "multi-country response" to the ordeal in an effort to prevent further spread.

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The concerted effort comes amid concerns over the Andes strain of the hantavirus after passengers aboard the MV Hondius cruise ship contracted the rodent-borne disease and grew ill.

The ship arrived early Sunday off the Spanish island of Tenerife, where passengers began to disembark and fly to their home countries.

According to Reuters, Spanish officials said passengers are being tested by local health authorities to ensure they are asymptomatic before being transported ashore in small boats.

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Spanish health authorities confirmed that the first plane carrying the Spanish passengers has departed for a military hospital in Madrid, where they will remain under quarantine.

American MV Hondius passengers will be flown to a medical center in Nebraska after being allowed to disembark, per prior reporting.

Kerkhove said WHO's recommendation is that a 42-day active follow-up period succeed passengers' return to their respective home countries.

"This would include health checks by authorities and either be quarantined at home or quarantined in a medical facility," she explained.

A Centers for Disease Control and Prevention (CDC) official told ABC News on Saturday morning that federal officials currently do not plan to mandate quarantine when the American passengers arrive in Nebraska.

They will instead be screened upon arrival in the U.S. and either stay briefly at Nebraska's National Quarantine Unit or return home to monitor for symptoms for 42 days while staying in contact with local health authorities, the official said.

Fox News' Michael Sinkewicz contributed to this report.