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Hantavirus “lives” in Washington – take these precautions to avoid it

1-5 Washington state residents get sick with hantavirus every year

SNOHOMISH COUNTY, Wash. – The recent cases of hantavirus from California’s Yosemite Park remind us in Washington that the same serious illness is possible here where deer mice live, mostly in rural areas. The virus affects the lungs, and the infection can cause death in up to 50 percent of the people who develop symptoms.

The state Department of Health reports that about 14% of deer mice tested in Washington have been infected. One human case of hantavirus has been identified in the state so far this year.

What are the symptoms of hantavirus?

Symptoms include fever, chills, muscle aches, and sometimes nausea, vomiting, and abdominal pain. The muscle aches are often severe. Persons with hantavirus develop coughing and shortness of breath from a few days to a week after onset of other symptoms, followed by respiratory distress.

How is hantavirus spread?

You can be exposed to hantavirus by inhaling dust after disturbing deer mouse nests or breathing in closed spaces where they live. Deer mice spread the virus in their urine, saliva, droppings, and nesting materials. Person-to-person spread of hantavirus has not occurred in the United States.

Prevention tips

  • Keep mice away. Clear the area within 100 feet of your house of junk piles, debris, and other areas where mice will nest. Keep weeds, brush, and grass cut. Plug up, screen, or cover all openings in your house larger than ¼ inch wide. Use steel wool to plug holes around the base of buildings. Stack firewood, lumber, and hay 12 inches off the ground and as far away from the house as possible. Use snap traps to catch the rodents.  
  • Remove food sources. Store pet food, grains, and animal feed in covered containers. Use a trash can with a tight-fitting lid for kitchen garbage and food scraps.
  • Clean up infested buildings. Air out infested buildings at least 30 minutes before entering. Wear rubber gloves when handling contaminated traps or mice. Do not dry dust, sweep, or vacuum. Wet mop with a disinfected solution. Wet down nests and other contaminated material with disinfectant (1 cup bleach diluted in 10 cups water OR phenol-based cleaner, OR other disinfectant) and discard the material by double-bagging it in zip-lock bags. Put it in the garbage.

Hantavirus is a Washington state reportable disease; confirmed cases are reported by health care providers to local health departments to help track the spread. If providers or the public have questions about hantavirus, contact Snohomish Health District Communicable Disease Surveillance and Response at 425.339.5278, Monday through Friday, 8 a.m. to 5 p.m.

Find more information about the Health District at

Established in 1959, the Snohomish Health District works for a safer and healthier community through disease prevention, health promotion, and protection from environmental threats. Find more information about the Health District at