Eighteen Americans who sailed aboard the Antarctic expedition cruise ship MV Hondius are now under medical quarantine in the United States after a hantavirus outbreak killed three people on the vessel and sickened others. At least one of the quarantined passengers has tested positive for the Andes variant of hantavirus, the only type known to spread between humans, and has been moved into a high-level isolation unit at the University of Nebraska Medical Center in Omaha. The rest are being monitored in specialized facilities as federal health officials work to determine how far the virus spread during the voyage.
A federal airlift to biocontainment
Sixteen U.S. citizens landed at Offutt Air Force Base near Omaha on a State Department-chartered plane from the Canary Islands, where the MV Hondius had been diverted during the outbreak response. Fifteen were placed in UNMC’s National Quarantine Unit. The sixteenth, who had previously tested positive for Andes hantavirus but was not showing symptoms, was taken directly to the adjacent Nebraska Biocontainment Unit for closer monitoring and repeat testing. Two more Americans were sent to a facility at Emory University in Atlanta, bringing the total under medical watch to 18.
The Department of Health and Human Services confirmed the federal coordination behind the operation, describing UNMC as a Regional Emerging Special Pathogen Treatment Center designated by the Administration for Strategic Preparedness and Response. CDC teams deployed both to the Canary Islands, where exposed passengers had been held before the flight, and to Offutt Air Force Base to support the arrival.
The CDC stated that the risk to the broader American public from this outbreak is extremely low.
What happened aboard the MV Hondius
The MV Hondius, operated by Oceanwide Expeditions, is a polar expedition vessel that carries small groups of passengers to Antarctica and other remote destinations. The World Health Organization issued a multi-country outbreak notice identifying the Andes virus as the pathogen behind the cluster. As of May 4, WHO reported two confirmed cases, five suspected cases, and three deaths among the 147 passengers and crew on board.
The CDC’s Health Alert Network circulated a clinician advisory summarizing the outbreak and linking to genomic sequence data published on Virological.org, giving researchers and hospitals a direct way to characterize the strain involved.
How the virus moved through the ship has not been established. Hantavirus infections are traditionally tied to contact with rodent droppings, urine, or saliva, or to breathing in aerosolized particles from contaminated material. The Andes variant stands apart from other hantaviruses because it is the only one documented to transmit from person to person in certain conditions. Whether the ship’s ventilation system, shared living spaces, or shore excursions played a role in this cluster remains an open question. Genomic sequencing referenced in the CDC’s health alert may eventually clarify whether the shipboard strain differs from land-based isolates in ways that affect how it spreads, but that analysis has not been completed or released publicly.
Why Andes hantavirus worries public health officials
Hantaviruses can cause hantavirus pulmonary syndrome, a severe respiratory illness that progresses from fever and muscle aches to fluid in the lungs and, in serious cases, respiratory failure. The case fatality rate for hantavirus pulmonary syndrome in the Americas has historically ranged from roughly 30% to 40%, according to the Pan American Health Organization, though outcomes vary by strain and access to supportive care. Symptoms typically appear one to five weeks after exposure, which means the quarantine window for the Hondius passengers could stretch several more weeks before officials can be confident no additional cases will emerge.
Most hantaviruses do not pass between people at all. The Andes variant’s documented ability to do so, first identified in outbreaks in Argentina and Chile, is what elevates the concern around a cluster in a confined setting like a cruise ship. That distinction is also why federal officials chose biocontainment-level facilities rather than standard hospital isolation for the returning passengers.
Testing complications and an early release
At least one quarantined passenger has already been cleared and sent home after U.S.-based testing overturned earlier results. The passenger, an oncologist profiled by the Associated Press, had been flagged by overseas testing in the Canary Islands that produced inconclusive results. After retesting at UNMC, the individual was found to be negative and released from the biocontainment unit.
CDC official David Fitter attributed the discrepancy to differences between overseas laboratory protocols and U.S. retesting standards. The case raises a practical question for the remaining passengers: how many of them could see their status change as American labs reprocess samples that were initially read as inconclusive abroad?
UNMC has confirmed that the remaining passengers are being assessed and monitored but has not disclosed how many, if any, have developed symptoms or returned additional positive results during their time in Omaha. Patient outcomes beyond the single asymptomatic positive case and the cleared oncologist are not detailed in any available institutional statement.
What the combined count of 18 actually represents
No single federal statement has confirmed 18 as a formal tally of quarantined Americans. The figure comes from combining UNMC’s count of 16 passengers in Omaha with the two individuals monitored at Emory. Whether additional exposed passengers from other countries are being tracked under separate national health systems is not addressed in available U.S. government communications. The WHO outbreak notice covers the full multinational passenger manifest, but country-by-country quarantine figures have not been published.
What comes next for the quarantined passengers
The quarantine and monitoring period at UNMC is expected to produce clearer answers in the coming weeks as U.S.-based laboratory results replace the inconclusive overseas testing that complicated early case counts. Given the one-to-five-week incubation window for hantavirus, some passengers may not develop symptoms, if they are going to, until well into late May or early June 2026.
For anyone who traveled on the MV Hondius or had contact with passengers after disembarkation, the CDC says it is developing specific health guidance. The agency’s position remains that the general public faces extremely low risk, but exposed individuals should follow instructions from public health authorities and seek medical attention if they develop fever, muscle aches, or respiratory symptoms.
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*This article was researched with the help of AI, with human editors creating the final content.
