The MV Hondius cruise outbreak has put hantavirus back in the spotlight, touching passengers who sailed from Argentina and sparking monitoring in states including Texas, Virginia, Georgia, Arizona and California, with infectious disease expert Luis Marcos of Stony Brook Medicine weighing in on risks, transmission and what health systems should prepare for.
Health officials say the expedition ship reported multiple illnesses that led to three deaths and several confirmed cases, and those figures have prompted follow-up investigations across continents. Authorities are tracking people who disembarked in different states, and public concern is focused on how this rodent-borne illness moves and where it might show up next. The circumstances — a couple infected while in Argentina, an incubation window that can stretch weeks, and subsequent spread aboard a vessel — make the situation unusual for the U.S. experience with hantavirus.
On the long view, hantavirus is not new to the United States; surveillance through recent decades has recorded hundreds of cases. “Most of these cases have been west of the Mississippi River, and classically the risk factors are being in contact with feces and urine from rodents,” Marcos told Fox News Digital. That pattern has guided public health messaging for years, focusing on rodent exposure in rural and peri-urban settings more than on casual community spread.
Most hantavirus strains in North America are not passed from person to person and are typically picked up when people inhale dust contaminated by rodent droppings, urine or saliva, or touch contaminated surfaces and then touch their face. However, the Andean strain that circulates in parts of South America can spread between people, and that distinction matters now because investigators believe the cruise incident involves that particular pattern. “The only proven human-to-human transmission has been with the Andean virus from South America — and that’s what’s happening now,” Marcos told Fox News Digital.
Symptoms often begin like a bad flu, with fever and muscle aches that can be mistaken for more common respiratory viruses such as influenza or COVID. “They were not symptomatic at all — the incubation period can be one, two, three or four weeks,” Marcos said, which complicates efforts to identify and isolate contagious individuals before they travel. Clinical presentations vary, and many cases will be mild, while a smaller share progresses to severe illness.
“Some people may have mild disease, so not everybody will be very, very sick,” the doctor noted, but clinicians stay alert because a subset can deteriorate rapidly. In the most severe form, hantavirus pulmonary syndrome fills the lungs with fluid and often requires intensive respiratory support. “The mortality rate [among those with HPS] is between 30% and 60% — so yes, it’s a deadly virus,” the doctor added.
Person-to-person spread requires close contact, and public health investigators stress that the transmission dynamics for hantavirus differ from airborne viruses like COVID. “It has to be really, really close contact,” he said. “The transmission is not as efficient as other viruses.” That means everyday encounters are unlikely to fuel broad community outbreaks, but household or prolonged close-contact exposures, especially in poorly ventilated settings, can raise risk.
Given the long incubation window, quarantine and follow-up for exposed passengers are part of the response strategy. “For this cruise, it’s important to have people in quarantine for a period of time,” he said, and health teams will likely monitor contacts for several weeks to catch late-developing cases. “The longest incubation period has been 56 days or so, so two months, roughly,” Marcos said. “But most cases will get sick within two to three weeks.”
Treatment remains supportive because there are no approved antivirals or vaccines for hantavirus in the United States at this time, although candidates are in development. “So what happens is the patient will end up in the hospital. We will do supportive care, which means if your lungs are full of fluid, you will require a ventilator until you know the virus runs its course,” Marcos said. Hospitals will lean on intensive care and respiratory support if and when severe cases arrive.
Despite the severity of HPS in some patients, Marcos emphasized that the chance of a global pandemic from hantavirus is very low because of its transmission limits. “I don’t feel a strong risk of a pandemic,” he told Fox News Digital. “The transmission is not like COVID. It’s very different.” He added a practical timeline for watching the outbreak: “I really think this is going to go away in the next two to three weeks, and we will know exactly the number of cases,” he added.
Practical prevention still matters: wear gloves and a mask when cleaning spaces that may harbor rodents, ventilate enclosed areas, and wash hands often after potential exposures. Public health teams across states including Texas, Virginia, Georgia, Arizona and California are following up with returned passengers and contacts while experts continue lab testing to pin down the outbreak’s scope and linkages to travel in Argentina and aboard the MV Hondius.
