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Hantavirus, a rare, rodent-borne pathogen that triggers a deadly respiratory illness, is going viral.

Previously a topic confined largely to textbooks, media mentions of the virus — as well as related internet search queries — have spiked exponentially over the past two weeks compared to last year. The surge follows an outbreak of the virus' Andes strain aboard a Dutch expedition cruise ship, which saw a rare instance of human-to-human transmission — the first documented in 30 years. Three of the 11 cases connected to the ship proved fatal.

Trained virologist Jason Upton isn't pushing the panic button.

We asked the associate professor of biological sciences in the College of Sciences and Mathematics to help separate fact from viral fiction and provide expert context to the contagious consternation persisting among a post-COVID public.

The History of Hantavirus

How long has Hantavirus been on the scientific radar?

Upton: Oh, for a long time. The first hantavirus was isolated in 1978 as the etiologic agent of Korean Hemorrhagic fever, which people had been trying to understand since the Korean war. One of the largest, most terrifying outbreaks happened back in 1993 in the Four Corners area where Arizona, Colorado, Utah and New Mexico meet. It’s something we’ve been studying for decades. It can be pretty nasty, but it isn’t exactly a super-common thing. There’s only been around 900 human cases in the United States since we started surveillance in 1993.

You mentioned the 1993 outbreak. How did that start?

Upton: It was originally recognized as a number of unexplained deaths clustered in that arid part of the Southwest. When the dust literally settled, they isolated a novel Hantavirus, eventually named Sin Nombre Virus, that nobody had really worked with before. One of the guys I trained with as a graduate student had been at the CDC at the time. He was one of those BSL-4 "spacesuit" guys who opened the packages and did the initial characterization of the virus.

In early 2025, actor Gene Hackman’s wife tragically died from the virus. Is that a typical case?

Upton: I’m not sure I’d call any human case of Hantavirus typical, but it certainly fits a recognizable pattern. Betsy Arakawa’s cause of death was listed as pulmonary distress due to a Hantavirus infection. In cases like that, transmission usually involves very specific conditions in a location with significant evidence of rodent droppings and feces.

Breaking down the Outbreak

How does Hantavirus actually jump from rodents to humans?

Upton: In dry areas, rodent urine, saliva and droppings desiccate — they dry out and turn into dust. If you’re banging around in an old building or warehouse and kick up that dust, you can inhale it. That’s thought to be the most likely method of transmission. It’s also important to note that we’re talking about wild rodents, like deer mice, usually in rural areas. The typical urban house mice are not normal carriers of hantavirus. 

What about the current cruise ship scare? People are worried because they’re hearing about person-to-person spread.

Upton: The strain everyone is talking about right now is the Andes strain. It’s been known since the mid-1990s that this particular strain has the capacity for person-to-person transmission, but it’s very uncommon and the conditions required for that to happen are still quite high. It’s not like the flu or COVID. On a ship, you have incredibly close quarters in dining areas and hallways, which allows diseases to move through those population more easily.

How worried should we be?

Personally, I’m not grabbing a mask. While it’s worth paying attention to, it isn’t worth being panicky about. If I were going to worry about a virus, I’d worry about highly pathogenic avian flu, like H5N1. It’s been smoldering for years in avian populations worldwide and has a potential for adapting to humans in a way that could cause a real problem.