Pitkin County Epidemiologist Clarifies Hantavirus Strain and Cleanup Tips

The air in a dusty attic or a quiet shed doesn’t just smell of old wood and insulation; it smells of potential, a faint, metallic tang that hangs heavy in the stillness. It’s the scent of history, or perhaps, the scent of a virus waiting to be inhaled. That’s the visceral reality of hantavirus, a threat that has locals glancing nervously at the sky and wondering if the next breath they take will be their last. The headlines have been screaming about a cruise ship, the MV Hondius, and a terrifying new strain of hantavirus that spreads from person to person, turning a leisurely vacation into a medical nightmare. It’s easy to let that international drama bleed into your local anxiety, to worry that the same airborne terror is lurking in the high country just beyond your driveway.

But here is the counterintuitive truth that Pitkin County Public Health is trying to drill into our collective skull: the monster on the ship is not the monster in your shed.

Carly Senst, the county’s epidemiologist, has confirmed what many of us suspected but needed a scientist to validate — the strain currently circulating in Colorado is the Sin Nombre Virus, and it is not the Andes strain linked to the Hondius outbreak. The Andes strain, which has the rare ability to jump between humans, is not found here. As of May 19, the Colorado Department of Public Health and Environment is aware of zero Coloradans exposed to that specific cruise ship-linked strain. We are not facing a crisis; we are facing a familiar, albeit serious, endemic reality.

Hantavirus is endemic to Colorado, Senst said. It’s part of the landscape, as natural as the aspen leaves turning gold in October. Yet, the distinction matters because the stakes are different. While the Andes strain is terrifying in its transmissibility, the Sin Nombre Virus is a stealthy, severe individual case. There have been 132 cases reported in the state between 1992 and 2025, an average of just four cases per year. That’s a very low amount, Senst noted. It’s rare. But when it hits, it hits hard. The mortality rate for those who test positive is a staggering 36%. So far in 2026, one of the two confirmed cases in the state led to a fatality.

It’s rare, but all hantavirus is severe, Senst added. This is a serious virus that we don’t want anyone to get.

The confusion stems from the symptoms. Hantavirus presents like any other respiratory illness — a fever, general malaise, fatigue, a cough. But the transition from "just a cold" to "medical emergency" is often extremely quick. The key, Senst emphasized, is prevention, specifically how you clean up the evidence of the carriers: the deer mice. We’ve all been taught to sweep. We’ve all grabbed a broom to clear out the cobwebs in the garage. But sweeping or vacuuming is the exact opposite of what you want to do. It kicks up that dust, that microscopic cloud of dried urine and feces, making it more infectious and more dangerous.

Instead, you need a disinfectant or a bleach solution, one and a half cups of household bleach in one gallon of water; to wet the area before you disturb it. You let the moisture weigh down the dust before you wipe it away. It’s a small shift in routine, a change in how you interact with the physical space you inhabit, but it’s the difference between inhaling a virus and staying healthy.

There’s a warmth to the way Senst speaks about this, not because it’s a mild illness, but because she’s not panicking. She’s not worried about the Hondius strain arriving in our rural backyards. The risk isn’t zero, because this is a rural area where mice are mice, but it’s a manageable risk. It’s a known quantity. You can feel it in the way the county has framed the message: don’t sweep. Bleach it. Breathe easy.

Outside, the wind picks up, rattling the dry stalks of last year’s grass against the siding of the house. It’s just wind, carrying pollen and dust, but if you listen closely, you can hear the quiet, persistent work of nature, and the small, furry residents who remind us that we share this space, whether we like it or not.