A hantavirus outbreak on the MV Hondius cruise ship has captured the attention of the world. The Dutch-flagged ship was cruising the Antarctic region as a part of a growing boom of eco-tourism, according to Reuters . At the time of writing, at least three passengers have died, and others have been exposed to the disease. Rodents like rats and mice are typical culprits for carrying the disease, but it can also be transmitted to humans. While not an epidemiologist, the sub-Antarctic destination prompted questions for me about connections between hantavirus and weather. Here’s what I found.

The ship, which had 147 passengers and crew on board, sailed from the southern tip of Argentina to the Cape Verde islands. The journey included a long stretch across the southern Atlantic passing places like South Georgia Island, which is famous for its glaciers, snowy peaks, seals, and penguins. The ship departed on April 1 from Ushuaia, which is known as the southernmost city in the world.

Does Hantavirus Thrive In Certain Weather Conditions?

The answer seems to be a tentative yes, but it can vary. In the U.S. hantavirus is most common in the western part of the country, according to Los Alamos National Laboratory. Scientists at the lab concluded that hantavirus pulmonary syndrome (HPS) associated with hantavirus likely thrives in that part of the country because drier air in the west allows it to linger and become “aerosolized” rather than being washed away in wetter parts of the country. “HPS is an acute respiratory illness with a mortality rate of about 35% in the U.S., according to a LANL press release . It went on to say, ”Humans become infected with hantavirus when they inhale the airborne particles of feces and urine of disease-carrying rodents." Haemorrhagic fever with renal syndrome (HFRS) is also associated with hantavirus.

Temperature ranged from 48 degrees Fahrenheit to 37 degrees Fahrenheit on departure day in Ushuaia, according to The Weather Channel . Since this is the Southern Hemisphere, April is a transition month from the warm season to the cool season. A 2020 study focused on the northwestern part of Argentina found that temperature was a significant factor associated with rodent population levels and transmission. The study confirmed previous work in central Argentia that high rodent populations were preceded by warmer winters. The authors speculated that warmer winters affect seasonal breeding and the reproductive period, but more studies are required.

Argentina, like many parts of the world, has experienced warming in recent decades and the winter of 2025 exhibited extreme temperature volatility. Many parts of the country experienced unseasonably mild temperatures last winter, according to The Guardian . Experts believe changing climate may be playing a role. “Dr Raúl González Ittig, a biologist and professor at the National University of Córdoba, said he believed the increase was more closely linked to rodent behaviour, noting that there was a significant drought in 2023 and 2024, followed by increased rainfall in subsequent years, which meant greater vegetation cover and more food for the animals,” wrote The Guardian’s South American correspondent Tiago Rogero.

“In parts of South America, reported cases of hantavirus pulmonary syndrome have increased in recent years, with some regions experiencing higher fatality rates than historical averages,” said the website of the Chemical Abstract Services of the American Chemical Society. “These patterns are widely linked to environmental drivers, including rainfall variability, agricultural expansion, and land‑use change, which remain the predominant determinants of hantavirus transmission through their effects on rodent reservoir abundance and human exposure,” it continued.

A thorough review of weather and climate associations with human hantavirus infections was conducted in 2021. The study was published in the journal Pathogens and focused on Latin America and the Caribbean region. The primary finding as suggested above is that hantavirus is associated with precipitation and habitat type. Associations with humidity and temperature were mixed. The authors noted that weather-climate associations were complex and represented a web of uncertainty related to climate changes, land use practices, multiple hantavirus strains, and the identity of multiple hosts.

What jumps out at me is something that climate scientists have been concerned about for many years. The extremes on both sides of the ledger respond to warming climate. The “whiplash” of extreme dryness or wetness has implications for wildfires, agriculture, and perhaps hantavirus too.