Fox News senior medical analyst Dr. Marc Siegel explains the rodent-borne virus as officials race to track those exposed on the MV Hondius cruise ship on 'America Reports.'

Fear is generally far more virulent than the virus that causes it. This is the case with the current hantavirus outbreak unless something about the virus itself has changed, which is very unlikely.

As far as we know, the only thing that this hantavirus has in common with the SARS-CoV-2 virus that sparked the COVID pandemic is that both are single-stranded RNA viruses and both sparked outbreaks on cruise ships. Of course, the current hantavirus outbreak on the MV Hondius is sparking memories of the Diamond Princess, which departed from Japan in late January 2020 for a cruise of the Western Pacific. The cruise ended up being quarantined off Japan for two weeks, after 712 of the 3,711 people on board became infected with the new COVID-19 virus.

But that’s where the similarity ends. On the MV Hondius, which left from Argentina, where the Andes strain of hantavirus is found, eight patients have become infected, and three have died, in part because the Andes strain can cause highly dangerous and deadly hantavirus pulmonary syndrome, or HPS. Unfortunately, the Andes strain can lead to HPS, and, given the close confines of a cruise ship, the vessel is an optimal environment for the spread of contagions.

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One question that needs to be answered urgently is: Who or what carried the virus onto the ship? Was it an infected rodent or an infected person? If the story is true, as has been reported, that the Dutch couple got infected before they boarded the ship during a bird-watching trip through Argentina, Chile and Uruguay, where they likely became infected from rodent droppings, urine or saliva, then the eight cases that occurred are all due to human-to-human transmission, which is much less common than rodent-to-human spread. This at least raises the question whether the virus itself could have changed, as does the case of the flight attendant who appears to have acquired hantavirus from an elderly Dutch passenger who later died of it.

But it is far, far more likely that nothing about the virus itself has changed. The Andes strain can spread from one human to another, though with great difficulty. A study from Chile showed only 1% spread among household contacts and 17% among sexual contacts.

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A more recent study from Argentina also showed extremely limited person-to-person spread. "From November 2018 through February 2019, person-to-person transmission of Andes virus (ANDV) hantavirus pulmonary syndrome occurred in Chubut Province, Argentina, and resulted in 34 confirmed infections and 11 deaths."

Health workers in protective gear evacuate patients from the MV Hondius cruise ship at a port in Praia, Cape Verde, on May 6, 2026. (Misper Apawu/AP)

Fortunately, there are only 15 to 50 cases of hantavirus in the U.S. yearly and 150 to 300 cases in all of the Americas. The most common strain is the Sin Nombre strain, which does not pass from human to human. There are 10,000 to 100,000 cases in Europe and Asia every year, but they have all involved strains that don’t support human-to-human spread. Hantavirus remains essentially a rodent virus.

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Here are three things you need to know about hantavirus in order to protect yourself from the fear and myths that are circulating.

While it is true that human-to-human spread is possible, it requires extremely close contact, most often sexual contact, and has only been shown to occur with the Andes strain.

This is extremely unlikely. This virus spreads mainly among rodents. The numbers are consistent from year to year, there are very few cases in the Americas, and the chance of this increasing is very low without a major mutation.

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False. Not only is this virus very rare in the U.S. and very difficult to contract unless you come in direct contact with infected mouse or rat droppings, saliva or urine — as the wife of actor Gene Hackman did before dying of HPS — but, in addition, the deadly HPS manifestation — which has a fatality rate of about 40% — is much less common in U.S. cases than the more typical diarrhea, muscle aches and high fever.

Authorities in South Africa and Europe must trace contacts of any passengers who got off the hantavirus-infected ship, but at the same time, the risk to the general population remains extremely low.

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It is also prudent for public health officials to quarantine all the MV Hondius passengers and crew members, around 150 people, now with cabin isolation and strict disinfection protocols and upon arrival in the Canary Islands, since the incubation period can be up to eight weeks.

Virologists must also examine the genetic structure of the current Andes hantavirus that is circulating. Above all, it makes sense to counter the spread of fear with facts. Of course, a crucial part of this is for virologists to examine the structure of the Andes hantavirus that infected these passengers.

CLICK HERE TO READ MORE FROM DR. MARC SIEGEL

Marc Siegel, M.D. is a professor of medicine and medical director of Doctor Radio at NYU Langone Medical Center. He is Fox News Channel's senior medical analyst. His forthcoming book is "The Miracles Among Us: How God's Grace Plays a Role in Healing" (Fox Books, November 18, 2025) and author of "COVID: The Politics of Fear and the Power of Science." Follow him on X @drmarcsiegel.

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