Buenos Aires — Argentine authorities are investigating a hantavirus outbreak linked to an Atlantic cruise ship, amid a rising number of cases nationwide that experts associate with the effects of climate change. The Dutch-flagged MV Hondius, docked after departing Ushuaia, a southern city in Argentina, has reported multiple infections with the Andes virus, a strain of hantavirus native to South America.

Since June 2025, Argentina has recorded 101 hantavirus infections, about twice the number seen in the same period the previous year, according to the Argentine Health Ministry. The recent fatal cases aboard the cruise ship include a 70-year-old Dutch man who died on April 11, followed by his 69-year-old wife on April 26, and a German woman on May 2. The virus incubation period, ranging from one to eight weeks, complicates efforts to determine whether infections occurred before departure, during a stopover on a remote South Atlantic island, or aboard the vessel itself.

Health officials are focused on tracing the movements of infected passengers within Argentina prior to boarding. Investigators suspect that exposure may have occurred during a bird-watching excursion in Ushuaia, a hypothesis supported by the presence of clustered hantavirus cases in the forested Patagonian hills. The province of Tierra del Fuego, where Ushuaia is located, has not previously reported hantavirus infections.

Hantavirus pulmonary syndrome (HPS), caused by the Andes virus, is a severe respiratory disease with a high fatality rate. The ministry noted that mortality in recent cases has reached nearly 30%, doubling the previous five-year average of 15%. Transmission to humans typically occurs through contact with rodent excreta, including droppings, urine, or saliva.

Scientists link the surge in hantavirus cases to environmental changes driven by climate change. Warmer temperatures and shifting ecosystems have allowed rodent populations, especially those carrying the virus, to expand into new regions. Hugo Pizzi, an infectious disease specialist in Argentina, highlighted that rising temperatures have transformed the country’s climate, creating conditions favorable not only for dengue and yellow fever but also for hantavirus proliferation.

Variations in precipitation have further contributed to the outbreak. Periods of drought compel rodents to move in search of resources, while intense rainfall fosters vegetation growth that increases food supplies, supporting larger rodent populations and enhancing the potential for virus transmission. Raul González Ittig, a genetics professor and researcher, emphasized that increased rodent density raises the likelihood of the virus spreading both among animals and to humans.

Once primarily confined to southern Patagonia, hantavirus cases have shifted geographically. The Argentine Health Ministry reports that 83% of infections now occur in northern provinces, with recent incidents including the first 2026 case in Bariloche, a mountain resort in Río Negro Province. Authorities issued an alert in January concerning multiple deadly hantavirus outbreaks, including those in Buenos Aires Province, Argentina’s most populous region.

Public health officials are intensifying surveillance and contact tracing efforts to curb further spread, particularly given the disease’s early symptoms often mimic common flu, which can delay prompt medical attention. The outbreak aboard the MV Hondius may represent an isolated incident, but experts warn the virus’s geographic reach and impact are expanding amid ongoing environmental changes.