BUENOS AIRES (AP) — Authorities and experts in Argentina are trying to determine whether their country is the source of a deadly hantavirus outbreak affecting a cruise ship in the Atlantic.
The health emergency aboard the vessel, moored across the ocean, comes as the South American country reports a rise in hantavirus cases that many local public health researchers attribute to the recently accelerated effects of climate change. Argentina, from where the cruise to Antarctica departed, has consistently been ranked by the World Health Organization as the country with the highest incidence in Latin America of this rare rodent-borne disease.
Rising temperatures expand the reach of the virus because, in part, as heat increases and ecosystems shift, the rodents carrying the hantavirus can thrive in more places, researchers say. People typically contract the virus through exposure to rodent droppings, urine, or saliva.
“Climate change has entered Argentina and, with it, the country has faced many problems, such as dengue, Zika, chikungunya, and yellow fever. That shift may have fostered greater blooming and more seeds that serve as food for these rats,” said Hugo Pizzi, a prominent Argentine infectious disease specialist. “But there is no doubt that, as time passes, it seems to be spreading farther.”
The Argentine Ministry of Health reported on Tuesday that 101 hantavirus infections had been logged since June 2025, roughly double the cases counted in the same period the year before.
A hantavirus present in South America, called the Andes virus, can cause a severe and often fatal lung disease known as hantavirus pulmonary syndrome. The illness caused deaths in nearly a third of cases last year, according to the Argentine Health Ministry, above the five-year average mortality rate of about 15%.
Hantavirus typically spreads by inhaling dust contaminated with rodent excrement and can be transmitted from person to person, though that is rare, according to the WHO, whose lead epidemics expert said the risk to the public is low. The Andes strain is the only hantavirus known to be transmissible from human to human.
Authorities said that passengers aboard the MV Hondius tested positive for Andes virus. Argentina said on Wednesday that it was sending genetic material of the Andes virus and testing equipment to help Spain, Senegal, South Africa, the Netherlands, and the United Kingdom detect it.
The cause of the infection is still under investigation.
Argentine authorities are trying to determine why parts of the country the infected passengers traveled through before boarding the Dutch-flagged cruise ship in Ushuaia, a southern Argentine city known as the end of the world. Once they know the itineraries, they say they will trace contacts, isolate those with the closest exposure, and conduct active monitoring to prevent further spread.
The World Health Organization, the UN health agency, said that the first death aboard, a 70-year-old Dutch man, occurred on April 11. His wife, also Dutch and 69, died on April 26. The third passenger, a German woman, died on May 2.
The virus can incubate for a period of one to eight weeks. That makes it difficult to know whether the passengers contracted it before leaving Argentina for Antarctica on April 1; during a scheduled stop on a remote South Atlantic island; or aboard the vessel.
In the Tierra del Fuego province, where the vessel lay docked for weeks before departure, no hantavirus case has ever been recorded. Before boarding, the Dutch couple toured Ushuaia and traveled to other parts of Argentina and Chile, the WHO noted.
The Argentine government’s main hypothesis is that the couple contracted the virus during a birdwatching excursion in Ushuaia, according to two researchers who spoke on the condition of anonymity because they are not authorized to brief the press while the investigation is ongoing. Authorities are also tracking the Dutch tourists’ steps across the forested slopes of Patagonia in southern Argentina, where several infections have been concentrated.
Because the initial symptoms resemble the fever and chills of flu, “a tourist may have said, ‘I’m just a cold,’ and not paid it much mind. In other words, it has all the ingredients to be a very dangerous virus,” said Raúl González Ittig, genetics professor at the National University of Córdoba and a researcher at CONICET, Argentina’s state scientific group.
Climate Change Drives Rodents to New Frontiers
In recent years Argentina endured a historic drought. But it also faced episodes of unexpectedly heavy rains, part of a broader pattern of extreme weather that scientists attribute to climate change.
Part of this variability has created conditions that have allowed hantavirus to thrive, according to experts. Dry periods force animals out of their usual habitats in search of food and water. The heavy rains spur vegetation growth, spreading seeds that attract rodents that feed on leaves.
“So when precipitation increases, food becomes more available. And that leads to larger rodent populations. And where there’s a case, there’s a rodent infected, the chance of transmission to other rodents increases,” and, eventually, to humans, explained Ittig.
Although hantavirus cases used to be limited to the southernmost reaches of Patagonia, now 83% are located in Argentina’s northern edge, according to the Health Ministry.
Argentina Issued Alerts Earlier This Year
The ministry issued a January alert about several deadly hantavirus outbreaks, including in Buenos Aires, the most populous province.
Rural hospitals are poorly equipped, and residents had little idea what had struck them.
Daisy Morinigo and David Delgado said that at first they thought their 14-year-old son had the flu when he developed fever and body aches. The doctors who first examined Rodrigo in the town of San Andrés de Giles sent him home with ibuprofen and instructions to rest.
But the energetic fourth-grader’s breathing worsened. On January 1 they rushed Rodrigo to intensive care. He died just two hours after a hantavirus test came back positive.
“I wouldn’t wish this pain on anyone in the world,” Delgado said.
