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Tips on avoiding hantavirus

Two cases of hantavirus in King County, one fatal, serve as a reminder to be careful when opening up closed cabins, working in crawl spaces, and dealing with rodent infestations in engines. Hantavirus can cause a rare but deadly disease called Hantavirus Pulmonary Syndrome (HPS). In Washington State hantavirus is carried primarily by deer mice. In Washington state it is not carried by rats. 

White-footed deer mouse is native to the San Juan Islands.  Photo from kwiaht.org

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.

Deer mice live in wooded areas in Washington state and can nest in nearby homes, sheds, cabins, other structures, and cars. A home or building does not need to be old or dilapidated to have a problem with rodents.

Who is at risk for hantavirus infection? 

Any activity that puts people in contact with rodent droppings, urine, saliva, or nesting materials can place you at risk for infection. Hantavirus is spread when virus-containing particles from rodent urine, droppings, or saliva are stirred into the air. It is important to avoid actions that raise dust, such as sweeping or vacuuming. Infection occurs when virus particles are breathed in.

Rodent infestation in and around the home (including infested sheds, outbuildings, cabins and barns) is the primary risk for hantavirus exposure. Cases of hantavirus associated with rodent-infested automobiles have also been reported.

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.

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.

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.

How do I prevent Hantavirus pulmonary syndrome? According to the state Dept of Health: 

Keep rodents out of your home and workplace. Always take precautions when cleaning, sealing and trapping rodent-infested areas.

Seal up cracks and gaps in buildings that are larger than 1/4 inch including window and door sills, under sinks around the pipes, in foundations, attics and any rodent entry hole.

Trap indoor rats and mice with snap traps.

Remove rodent food sources. Keep food (including pet food) in rodent proof containers.

Clean up rodent infested areas:

Wear rubber, latex, vinyl or nitrile gloves.

Do not stir up dust by vacuuming, sweeping, or any other means.

Thoroughly wet contaminated areas including trapped mice, droppings, and nests with a 10% hypochlorite (bleach) solution: Mix 1½ cups of household bleach in 1 gallon of water (or 1 part bleach to 9 parts water). Once everything is soaked for 10 minutes, remove all of the nest material, mice or droppings with damp towel and then mop or sponge the area with bleach solution.

Steam clean or shampoo upholstered furniture and carpets with evidence of rodent exposure.

Spray dead rodents with disinfectant and then double-bag along with all cleaning materials. Bury, burn, or throw out rodent in appropriate waste disposal system. Disinfect gloves with disinfectant or soap and water before taking them off.

After taking off the clean gloves, thoroughly wash hands with soap and water (or use a waterless alcohol-based hand rub when soap is not available).

What precautions should I use working, hiking, or camping outdoors?

Avoid coming into contact with rodents and rodent burrows or disturbing dens (such as pack rat nests).

Air out cabins and shelters, then check for signs of rodent infestation. Do not sweep out infested cabins. Instead, use the guidelines above for disinfecting cabins or shelters before sleeping in them.

Do not pitch tents or place sleeping bags near rodent droppings or burrows.

If possible, do not sleep on the bare ground. Use tents with floors or a ground cloth. Keep food in rodent-proof containers!

Handle trash according to site restrictions and keep it in rodent proof containers until disposed of.

Do not handle or feed wild rodents. 

The Center for Disease Control (CDC) website has information about  preventing rodent infestation and clean up rodent infestations.

Symptoms of hantavirus:


If you have been exposed to rodents or rodent infested buildings and have symptoms, see your doctor immediately and tell them about your possible rodent exposure. 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. People with hantavirus are usually hospitalized, and about one out of three people diagnosed with HPS have died.

Popular Mechanics magazine has an article about rodent infestations in cars. Signs of rodents include a foul odor, chewed wires or other components under the hood, and visible nesting material and excrement in the vehicle. (See this Popular Mechanics article on rodents in cars).

More information about hantavirus is available on the Washington State Department of Health website

Last modified onSunday, 26 March 2017 22:03