Avoid rodent droppings and nests to protect yourself

Summary: Local public health officials are investigating a new suspected case of hantavirus pulmonary syndrome (HPS) in an Issaquah woman. Test results are expected in the next two days, and an investigation is already underway to determine how and where the person may have been exposed to the deer mice that carry hantavirus. Members of the public are reminded to avoid rodent droppings and nests and to take precautions when cleaning up after rodents.

Story: Public Health – Seattle & King County has received a report of an Issaquah resident in her 50’s with symptoms consistent with HPS. The woman is currently hospitalized.

In February, a man from Issaquah in his 30s contracted hantavirus and subsequently died. Both cases lived near Squak Mountain but in different neighborhoods. Last November, a woman was exposed to deer mice near her home in Redmond. She contracted HPS, but survived.

Public Health does not believe the two cases in Issaquah are related but there are reports of increased numbers of deer mice seen in the area. We are making this announcement in order to raise public awareness about steps that the public can take to reduce the risk for hantavirus wherever deer mice are common. Deer mice do not live in urban settings in Washington, but prefer woodland areas such as the suburban foothills.

“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.”

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 for people concerned about hantavirus

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 specific guidance in cleaning up vehicles.)

Guidelines for cleaning up rodent nests and infected areas are available. 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.

Next steps in the investigation

If the current suspect case is confirmed as HPS, Public Health will continue investigating how and where this woman most likely became infected. We will be consulting with the Washington state Department of Fish and Wildlife to provide information on the ecology of deer mice locally, including whether there have been any changes either to the population of deer mice or to the prevalence of the hantavirus in the deer mice, and whether changes may be impacting the threat to humans. We are also consulting with the Centers for Disease Control and the Washington State Department of Health.

More about hantavirus

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

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 3 other cases reported to Public Health since 1997 where the people were thought to have been infected outside of the county.

More information

For additional information, visit the Public Health Insider blog and the hantavirus information page.