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Issaquah woman hospitalized for rare mouse-related virus

SEATTLE -- Health officials are investigating a new suspected case of a rare mouse-related virus in King County.

An Issaquah woman in her 50s showed symptoms consistent with hantavirus pulmonary syndrome (HPS). She is currently hospitalized. Test results are expected in the next two days.

HPS is contracted by breathing in hantavirus. This can happen when dust from dried rodent urine, saliva, and droppings that contain hantavirus are stirred up in the air.

In February, a man from Issaquah in his 30s contracted hantavirus and subsequently died.

Both cases lived near Squak Mountain but in different neighborhoods. Public health officials do not believe the two cases are related. But the cases suggest an increased risk for hantavirus exposure in some areas.

Last November, a woman was exposed to deer mice near her home in Redmond. She contracted hantavirus but survived.

“If this third case of HPS is confirmed it suggests that certain areas of the county are at increased risk compared to past years,” said Dr. Jeff Duchin, Health Officer for Public Health – Seattle & King County. “People who live near wooded areas where deer mice are common should take steps to keep rodents out of the home and other structures, and take precautions when cleaning up rodent nests and potentially contaminated spaces. Anyone who has had exposure to rodent nests or areas where rodents are living and who develops symptoms should see a health care provider promptly.”

Hantavirus is a rare disease in Washington state. Before 2016, the last case of hantavirus infection acquired in King County was in 2003.  There have also been three other cases reported to Public Health since 1997 where the people were thought to have been infected outside of the county.

In Washington, the only rodents that spread hantavirus are deer mice, which live in woodland areas and deserts. They have distinctive white underbellies and white sides. They are only distantly related to the common house mouse. Rats do not spread hantavirus in Washington

How hantavirus is contracted and signs and symptoms of HPS

A person gets HPS by breathing in hantavirus. This can happen when dust from dried rodent urine, saliva, and droppings that contain hantavirus are stirred up in the air. People can also get infected by touching rodent urine, droppings, or nesting materials that contain the virus, and then touching their eyes, nose, or mouth. It’s also possible to get HPS from a rodent bite. The disease does not spread person-to-person. Symptoms begin 1-8 weeks after inhaling the virus. It typically starts with 3-5 days of illness that is similar to the flu, including fever, sore muscles, headaches, nausea, vomiting, and fatigue. As the disease gets worse, it causes coughing and shortness of breath as fluid fills the lungs.

Additional advice:

The chance of being exposed to hantavirus is greatest when people work, play, or live in closed spaces where rodents are actively living. Many people who have contracted HPS reported that they had not seen rodents or their droppings before becoming ill. Therefore, if you live in an area where the deer mice are known to live, take precautions to prevent rodent infestations even if you do not see rodents or their droppings.

Potential risk activities for HPS include:

  • Opening or cleaning previously unused buildings, cabins, sheds, barns, garages and storage facilities (including those which have been closed during the winter) is a potential risk for hantavirus infections, especially in rural settings.
  • Housecleaning activities in and around homes with rodent infestations. Cleaning guidelines may be found at https://www.cdc.gov/rodents/cleaning/
  • Work-related exposure: Construction, utility and pest control workers can be exposed when they work in crawl spaces, under houses, or in vacant buildings that may have a rodent population.
  • Campers and hikers: Campers and hikers can be exposed when they use infested trail shelters or camp in other rodent habitats.
  • Exposure to cars, trailers, or mobile homes where rodents are living (see http://www.kingcounty.gov/depts/health/communicable-diseases/disease-control/hantavirus/cleaning.aspx for specific guidance in cleaning up vehicles.

Guidelines for cleaning up rodent nests and infected areas are available at:  https://www.cdc.gov/rodents/cleaning/.   Some people may prefer to consult with a pest control agency to help with rodents in the home or other structures. Public Health should be consulted and special precautions are indicated for cleaning homes or buildings with:

  • heavy rodent infestations (piles of feces, numerous nests or dead rodents)
  • vacant dwellings that have attracted rodents while unoccupied
  • dwellings and other structures that have been occupied by persons with confirmed hantavirus infection.
  • Public Health recommends hiring professional pest control services in these situations.

See your healthcare provider if you develop symptoms after being in contact with rodent nests or cleaning up areas where deer mice may have been living.