Argentine health officials and scientists are investigating whether the country is the source of a deadly hantavirus outbreak aboard the cruise ship MV Hondius. The health emergency on the vessel coincides with a surge in hantavirus cases in Argentina, which public health researchers attribute to accelerating effects of climate change.
Rising Cases in Argentina
The Argentine Health Ministry reported 101 hantavirus infections since June 2025, roughly double the caseload recorded over the same period the previous year. The Andes virus, a hantavirus found in South America, can cause hantavirus pulmonary syndrome, a severe and often fatal lung disease. The disease led to death in nearly a third of cases last year, up from an average mortality rate of 15 percent in the previous five years.
Argentina, the departure point for the Antarctic cruise, consistently has the highest incidence of this rare, rodent-borne disease in Latin America, according to the World Health Organization.
Climate Change as a Driver
Experts suggest that higher temperatures expand the virus's range. As it gets warmer and ecosystems change, hantavirus-carrying rodents can thrive in more places. People typically contract the virus from exposure to rodent droppings, urine, or saliva.
Hugo Pizzi, a prominent Argentine infectious disease specialist, stated: "Argentina has become more tropical because of climate change, and that has brought disruptions, like dengue and yellow fever, but also new tropical plants that produce seeds for mice to proliferate. There is no doubt that as time goes by, the hantavirus is spreading more and more."
Argentina has endured a historic drought in recent years but also bouts of unexpectedly intense rainfall, part of a broader pattern of wild weather attributed to climate change. This variability has created conditions that allow hantavirus to flourish. Dry spells drive animals out of their usual habitats in search of food and water, while heavy rain leads to vegetation growth that attracts rodents.
Raúl González Ittig, genetics professor at the National University of Córdoba and a researcher at CONICET, explained: "When precipitation increases, food availability increases, rodent populations grow, and if there are infected rodents, the chance of transmission between rodents — and eventually to humans — also increases."
MV Hondius Outbreak
Authorities have confirmed that passengers aboard the MV Hondius tested positive for the Andes virus. The first death on board, a 70-year-old Dutch man, occurred on April 11. His 69-year-old wife, also Dutch, died on April 26. A third passenger, a German woman, died on May 2.
The virus can incubate for between one and eight weeks, making it difficult to determine whether passengers contracted the virus before leaving Argentina for Antarctica on April 1, during a scheduled stop to a remote South Atlantic island, or aboard the ship. The province of Tierra del Fuego, where the vessel docked for weeks before departing, has never seen a case of hantavirus. Before boarding, the Dutch couple went sightseeing in Ushuaia and traveled elsewhere in Argentina and Chile, according to the WHO.
Argentina's leading hypothesis is that the couple contracted the virus during a bird-watching outing in Ushuaia, according to two investigators who spoke on condition of anonymity. Authorities are also tracing the Dutch tourists' footsteps through forested hillsides of Patagonia.
Because early symptoms resemble fever and chills of flu, "tourists might think they just have a cold and not take it seriously. That makes it particularly dangerous," said Ittig.
Changing Epidemiology
Although hantavirus cases were once limited to southern Patagonia, now 83 percent of cases occur in Argentina's far north, according to the Health Ministry. In January, the ministry issued an alert on several fatal hantavirus outbreaks, including in the most populous province of Buenos Aires.
On Tuesday, the mountain resort town of Bariloche recorded its first human hantavirus case of 2026, the government of Río Negro Province said. The patient was hospitalized on Wednesday.
Pizzi concluded: "With the climate changing, the epidemiological picture has completely changed. The ship may be an isolated case. But this virus isn't going anywhere."
What Is Hantavirus?
Hantavirus is mainly spread by contact with rodents or their urine, saliva, or droppings, particularly when the material is disturbed and becomes airborne. People are typically exposed around homes, cabins, or sheds, especially when cleaning enclosed spaces with little ventilation or entering areas with mouse droppings. The WHO says that while rare, hantaviruses may spread between people.
The US Centers for Disease Control and Prevention began tracking the virus after a 1993 outbreak in the Four Corners region. Most US cases are in Western states, with New Mexico and Arizona as hotspots.
Symptoms of Hantavirus
Infection can rapidly become life-threatening. Early symptoms include fever, chills, muscle aches, and headache. "Early in the illness, you really may not be able to tell the difference between hantavirus and having the flu," said Dr. Sonja Bartolome of UT Southwestern Medical Center.
Symptoms of hantavirus pulmonary syndrome usually appear one to eight weeks after contact. As the infection progresses, patients may experience chest tightness as the lungs fill with fluid. Hemorrhagic fever with renal syndrome typically develops within one to two weeks after exposure.
Death rates vary. Hantavirus pulmonary syndrome is fatal in nearly 40 percent of cases, while hemorrhagic fever with renal syndrome has a death rate of 1 to 15 percent, according to the CDC.
