Chile, Argentina report rise in deadly hantavirus cases
What began as a seasonal concern in rural areas of South America's Southern Cone has evolved into an international health alert after an outbreak detected aboard the expedition cruise ship MV Hondius.
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The Dutch cruise ship MV Hondius is anchored off the coast of the city of Praia on the island of Santiago, Cape Verde, on after Monday three people died onboard from an acute respiratory syndrome. The World Health Organization reported one confirmed case and five additional suspected cases of hantavirus infection on the vessel sailing in the Atlantic Ocean. (Photo Credit: Elton Monteiro/EPA)
May 7 (UPI) -- A sustained increase in hantavirus infections in Argentina and a sharp rise in fatal cases in Chile this year have raised concerns among health authorities, who link the situation to climate change and the transmission capacity of the Andes strain of the virus.
What began as a seasonal concern in rural areas of South America's Southern Cone has evolved into an international health alert after an outbreak detected aboard the expedition cruise ship MV Hondius.
The vessel, which departed from Ushuaia, Argentina, in March on a voyage toward the Arctic, has become a symbol of the risks associated with the Andes strain, the only hantavirus variant known to spread between humans through close contact, according to the World Health Organization.
WHO Director-General Tedros Adhanom Ghebreyesus said Thursday that five confirmed hantavirus cases and three suspected cases linked to the cruise have been identified. Three of the infected passengers have died, while one remains in intensive care in Johannesburg, South Africa, and another is hospitalized in Switzerland, Spanish newspaper El País reported.
So far in 2026, Chile has confirmed 39 hantavirus cases through May, with a fatality rate of 33%. The figures surpass 2025 totals, when Chile recorded 44 cases and eight deaths during the entire year. Most of the infected patients are men involved in rural and forestry activities, according to Chile's Health Ministry.
In Argentina, the National Epidemiological Bulletin has reported 42 confirmed cases this year. Local authorities are particularly concerned about the mortality rate, which has ranged between 31% and 39% in 2026, significantly above the historical average of about 22%.
Health experts warn that early hantavirus symptoms are often confused with influenza or COVID-19, delaying medical treatment even though the disease can rapidly progress into severe cardiopulmonary syndrome.
Researchers link the increase in infections to climate change. Milder and shorter winters in Patagonia and central Argentina have allowed larger populations of long-tailed pygmy rice rats, the primary carriers of the virus, to survive and reproduce more frequently.
Authorities have also detected the spread of the virus into more populated areas. In Argentina, the central region, including Buenos Aires, Santa Fe and Entre Ríos provinces, now accounts for more than 70% of reported cases, surpassing the historically affected Andean region.
Investigators believe the outbreak aboard the MV Hondius may have originated from initial exposure to infected rodents near ports or excursion sites before spreading among passengers and crew members.
According to media reports, the Dutch couple who died after the cruise had traveled extensively through Argentina, Chile and Uruguay before boarding the vessel. Authorities suspect they may have contracted the virus during an excursion near Ushuaia.
Argentine health officials said they have deployed operations to capture and test rodents in Tierra del Fuego province to determine whether the cruise-related infections originated there.
Chile's Health Ministry said in a statement that the reported primary cases had traveled through Chile during a period inconsistent with the virus' incubation timeline, suggesting the exposure most likely did not occur in the country.
Health authorities led by the World Health Organization have so far ruled out the risk of a global epidemic, describing the outbreak as a public health event of limited international concern.
Although concerns remain over the Andes strain's ability to spread between humans, experts said hantavirus does not transmit as easily as respiratory viruses such as COVID-19 because it requires prolonged close contact.
As a result, authorities consider the risk to the population outside the affected areas to be very low, provided isolation protocols and monitoring measures remain in place for passengers who were in contact with infected people.
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