The cruise ship left Ushuaia, Argentina, in April with plans to take 147 passengers and crew to some of the most remote places on Earth, including Antarctica. But the ship’s voyage, named MV Hondius, was interrupted by a rare virus that killed three people and infected several others.
Hantaviruses are an ancient family of rodent-borne pathogens that likely caused disease in humans long before they first appeared in medical records in the 1950s. The virus is transmitted to people through rodent excrement. It is often transmitted through inhalation of dust containing trace amounts of excrement. Andean hantavirus, the strain that infected the MV Hondius during a polar cruise, is one of the few hantaviruses known to cause hantavirus pulmonary syndrome, a rare but often fatal disease.
The Andes strain is also the only known hantavirus that can be transmitted from human to human. This characteristic has turned a rare rodent-borne disease into a multinational emergency just a few years after the world was brought to its knees by the COVID-19 pandemic.
The good news is that while the Andean hantavirus is extremely deadly, it is likely not as contagious as the new coronavirus. Nevertheless, the outbreak highlights the complexity of responding to infectious disease outbreaks, as international cooperation on public health issues becomes fractured and contentious, while overall increasing the likelihood of a global pandemic. A month before the first patient on the MV Hondius showed symptoms, Argentina formally completed the process of withdrawing from the World Health Organization, joining the United States from the Global Health Alliance, which exists primarily to coordinate responses to cross-border disease outbreaks of this type.
This emergency also presents another growing challenge to global public health. Climate change is changing rainfall, vegetation, and habitat conditions, affecting rodent populations. Experts say this change increases the likelihood that the pathogens these animals carry will spill over into human populations.
The incubation period for hantaviruses, which ranges from one to six weeks, means that the infection could have originated in one of the passengers’ home countries, but a possible culprit is that the ship stopped for bird watching near Ushuaia, a landfill site that attracts foraging rodents. Argentine health authorities have already recorded a spike in hantavirus cases this season. Since June 2025, 101 infections have been recorded, almost double the number from the same period last year.
The country’s Ministry of Health has not yet determined the cause of the surge, but research suggests climate change may be playing a role. Argentina and its South American neighbors endured years of severe drought from 2021 to 2024, with Argentina suffering its worst drought in more than 60 years in 2023 and extreme rainfall last year. Kirk Douglas, a senior scientist who studies hantaviruses and climate change at the University of the West Indies Cave Hill in Barbados, said extreme weather events exacerbated by global warming are changing rodent behavior.
Prolonged droughts can push rats and mice into populated areas in search of food, increasing the risk of people contracting the virus. When droughts are followed by sudden rains, trees and shrubs become stockpiled with nuts and seeds, which tend to benefit rodents and increase their numbers, but also increases the risk of animal-to-human transmission.
However, this does not mean there is a one-to-one relationship between rising global temperatures and risk from rodents, and climate change is not the only factor at play. A complex combination of natural and human-induced landscape changes can increase or decrease human-rodent contact. For example, increased temperature and humidity do not seem to affect hantavirus disease ecology as much as drought or precipitation.
“Hantavirus is sensitive “The changes that climate change brings will depend on what the current climate impacts are,” Douglas emphasized.
Due to its complexity, hantavirus risks are difficult to predict and easily overlooked. Hantavirus infections have been rare in the United States since federal surveillance began in 1993. By 2023, the latest year for which data is available, there were fewer than 1,000 total confirmed cases. Approximately 35% of these cases occurred west of the Mississippi River, and most were fatal.
As in South America, hantavirus trends in the United States may be changing. The most dangerous places, federal scientists said in a study published last year, are arid landscapes where homes are spread out, many types of rodents live in close proximity, and communities may have fewer resources to prevent and respond to disease. This situation applies to large areas of the American West.
