A 34-year-old Montana man who nearly died from hantavirus pulmonary syndrome last summer is speaking publicly for the first time about the experience, describing his illness as “like hell on earth” and urging outdoor enthusiasts to take the rare but potentially fatal disease more seriously. Marcus Delray, a hiking guide from Billings, was hospitalized for 19 days in July 2025 after exposure to rodent droppings at a backcountry shelter near the Beartooth Wilderness area. He was placed on mechanical ventilation for nearly a week before doctors were able to stabilize his condition.
Hantavirus is a rodent-borne illness transmitted primarily through contact with infected deer mice droppings, urine, or saliva. The virus does not spread from person to person, but inhaling disturbed particles from contaminated environments can lead to hantavirus pulmonary syndrome — a rare condition with a case fatality rate of approximately 38 percent, according to the Centers for Disease Control and Prevention. In the United States, several hundred cases have been reported since surveillance began in 1993, with the majority concentrated in the western and southwestern states.
Public health officials in Montana confirmed that 2025 saw an uptick in deer mouse activity across the northern Rockies, largely attributable to the previous winter’s mild temperatures, which allowed rodent populations to expand unchecked. Ecologists at the state wildlife agency estimated that deer mouse densities in certain mountain corridors were 40 to 60 percent above the five-year average. Warmer-than-normal spring and summer conditions further concentrated rodent populations in and around human-use structures such as trail shelters, hunting cabins, and campsite food-storage boxes.
Delray, who had guided wilderness trips for nearly a decade, said he initially dismissed his symptoms — a low-grade fever, muscle aches, and fatigue — as a routine summer cold. “I thought I was just run down from a long season,” he said in an interview from his home. “By day four I couldn’t breathe. I genuinely thought I was going to die.” He was airlifted from a rural clinic to a regional medical center in Billings, where physicians diagnosed hantavirus following a blood panel that detected antibodies to Sin Nombre virus, the most common hantavirus strain circulating in North America.
Dr. Priscilla Vann, an infectious disease specialist at the medical center who oversaw Delray’s care, said his survival was attributable in part to rapid transfer to a facility equipped with extracorporeal membrane oxygenation, or ECMO, technology. “We see perhaps one or two cases of hantavirus in this region every year,” Dr. Vann said. “The window between the onset of respiratory symptoms and critical deterioration can be extremely short — sometimes less than 48 hours. The fact that Marcus was transported quickly made a significant difference.” She noted that there is no specific antiviral approved for hantavirus and that treatment remains supportive, focusing on managing fluid balance and providing respiratory assistance.
Prevention remains the most effective tool against hantavirus. Public health authorities recommend that campers and outdoor workers avoid sweeping or vacuuming areas where rodent droppings may be present, instead using wet cleaning methods with a diluted bleach solution. Ventilating closed structures such as cabins for at least 30 minutes before entry, wearing gloves, and using an N95 respirator mask when cleaning potentially contaminated spaces are also advised. The CDC further recommends against sleeping on bare ground in areas of known rodent activity.
Delray, who has recovered most of his lung function but still experiences mild shortness of breath on strenuous climbs, said he now incorporates a safety briefing about hantavirus into every guided trip he leads. He has also partnered with a state public health outreach program to distribute educational materials at trailheads across the Beartooth and Absaroka ranges. “If my story keeps even one person from ignoring the symptoms, then going through all of that was worth something,” he said.
Health officials say they are watching regional rodent population trends heading into the 2026 outdoor season and will issue updated guidance to backcountry users if elevated risk conditions persist. Visitors to rural and wilderness areas in hantavirus-endemic regions are encouraged to report unusually high rodent sightings to local wildlife authorities and to seek immediate medical attention if they develop fever, muscle pain, or breathing difficulties within six weeks of potential exposure. Awareness, officials stress, remains the single most powerful tool available to the public in the absence of a licensed hantavirus vaccine.