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Justin Caporusso/Caporusso Communications justin@caporussocommunications.com


(916) 412-0571


FOR IMMEDIATE RELEASE

Second Hantavirus-Related Death Confirmed in Mono County


MONO COUNTY, Calif. (MARCH 26, 2025) – Mono County Public Health has confirmed a second death


related to Hantavirus in the Town of Mammoth Lakes. Hantavirus is a serious and often fatal illness


spread primarily through contact with infected deer mouse droppings, urine, or saliva. Deer mice


are widespread in the Eastern Sierra region.


“Hantavirus Pulmonary Syndrome is uncommon but extremely dangerous,” said Dr. Tom Boo, Mono County


Health Officer. “We urge residents and visitors to pay attention to the presence of mice indoors


and other enclosed spaces and take precautions to reduce the risk of infection, especially when


cleaning up areas where rodent activity is present.”

Ongoing Investigation


Each Hantavirus case is investigated by local and state public health officials. The exposure for


one of the two confirmed cases this year may have occurred while vacuuming rodent waste, while the


other individual was likely exposed at home during a known infestation. A third possible case is


currently under investigation. Prior to these cases, the last confirmed Hantavirus infections in


Mono County occurred in 2019.

Since the first local case in 1993, Mono County has recorded 26 confirmed Hantavirus cases tied to


exposures in the county—the most in the State of California. Twenty of these infections were in


county residents, and six in people who visited Mono County and became infected. Two cases within a


three-week span during late winter are unusual, as most cases are typically reported in spring and


summer.


Rodent trapping in places where the first case may have been exposed found that 27% of captured


deer mice tested positive for Hantavirus—consistent with the county’s typical baseline of around


25%.

Health Risks and Symptoms


Hantavirus causes a severe illness that progresses rapidly once the lungs are involved. Early


symptoms usually include fever, fatigue, headache and muscle aches, sometimes with gastrointestinal


symptoms, followed by coughing and shortness of breath. The disease is often fatal, with a


mortality rate of approximately 30%. Prompt diagnosis and treatment improve outcomes, but testing


is only available in specialized laboratories, making early recognition challenging.

Prevention is Key


Public Health urges community members and visitors to remain vigilant for signs of rodent activity,


particularly in homes, cabins, sheds, garages, and other enclosed spaces. Infested vehicles may be


risky too. Follow these guidelines to reduce your risk:

• Seal up all gaps in your home larger than a pencil’s width to prevent mice from


entering.


• Store food in rodent-proof containers.


• Trap mice using snap traps (not glue or live traps).


• Avoid vacuuming or sweeping rodent droppings, nests, or urine.


• Air out enclosed spaces for at least 30 minutes before activities.


• Spray contaminated areas with a disinfectant or a freshly made 10% bleach solution and let sit


for five minutes before wiping clean.


• Wear gloves and an N-95 (or higher) mask when cleaning. Contact Public Health for free N-95


masks.

Do not eat food that may have been contaminated by rodents, and always wash your hands thoroughly


after any potential exposure.

Mono County Public Health can be reached at (760) 924-1830. The California Department of Public


Health has more hantavirus information at:


cdph.ca.gov/Programs/CID/DCDC/Pages/HantavirusPulmonarySyndrome.aspx.

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