Climate Change and Hantavirus: How Warming Trends May Fuel Deadly Rodent-Borne Outbreaks

The MV Hondius, a cruise ship that departed Ushuaia, Argentina, in April 2025, was forced to cut its voyage short after a rare hantavirus outbreak killed three passengers and infected several others. The ship was en route to remote destinations, including Antarctica, with 147 passengers and crew onboard.

Hantaviruses are an ancient family of rodent-borne pathogens that likely infected humans long before they were first recorded in medical literature during the 1950s. Transmission typically occurs through the inhalation of dust contaminated with rodent excreta. The Andes hantavirus, the strain responsible for the outbreak on the MV Hondius, is one of the few known to cause hantavirus pulmonary syndrome—a rare but often fatal illness. Unlike most hantaviruses, the Andes strain can be transmitted from person to person, transforming a rodent-borne infection into a potential international health emergency.

While the Andes hantavirus is highly deadly, experts emphasize that it is far less transmissible than COVID-19. However, the outbreak underscores the challenges of responding to infectious diseases in an era of fractured global cooperation. Just a month before the first cases were reported on the MV Hondius, Argentina officially withdrew from the World Health Organization (WHO), joining the U.S. in exiting a global health alliance designed to coordinate responses to cross-border disease outbreaks.

Climate Change and the Rising Threat of Hantavirus

The outbreak also highlights another growing concern for global public health: climate change is altering environmental conditions in ways that increase the risk of rodent-borne diseases. Changes in rainfall, vegetation, and habitat are influencing rodent populations, which in turn raises the likelihood of pathogen spillover into human communities.

A possible source of the MV Hondius outbreak may have been a stop near Ushuaia for a birding expedition. The region is home to a landfill that attracts rodents searching for food. Argentina’s health authorities have reported a sharp rise in hantavirus cases this season, with 101 infections recorded since June 2025—nearly double the number from the same period in 2024. While the exact cause of the surge remains undetermined, research suggests that climate change may be a contributing factor.

Between 2021 and 2024, South America, including Argentina, experienced severe droughts, including the country’s worst dry spell in over 60 years in 2023, followed by extreme rainfall in 2024. These weather extremes, exacerbated by global warming, are altering rodent behavior, according to Kirk Douglas, a senior scientist at the University of the West Indies, Cave Hill, in Barbados, who studies hantaviruses and climate change.

"Prolonged drought sends rats and mice into populated areas in search of food, which increases human exposure to their waste and the pathogens they carry."

As global temperatures rise, the frequency and intensity of extreme weather events are expected to grow, further disrupting ecosystems and increasing the risk of zoonotic diseases—those transmitted from animals to humans. The hantavirus outbreak on the MV Hondius serves as a stark reminder of how interconnected climate change and public health truly are.