Hantavirus is a virus carried by some rodents. In Washington State, deer mice are the only animals known to carry it and it is estimated that about 14% of the deer mouse population is infected. Hantavirus can cause a rare but deadly disease called hantavirus pulmonary syndrome (HPS). You can get HPS by breathing in hantavirus. This can happen when rodent urine and droppings that contain hantavirus are stirred up in the air. You can also get infected by touching mouse urine, droppings, or nesting materials that contain the virus, and then touching your eyes, nose, or mouth. It is possible, yet even more rare, to get HPS from a mouse or rat bite. The disease does not spread person-to-person.
Certain activities can put you at risk such as:
- Improperly cleaning up mouse and rat urine, droppings, and nests.
- Cleaning a shed, cabin or other small enclosure than has been closed for some time.
- Working in areas where mice may live (such as barns).
- Exposure to mouse nesting materials or droppings in a car, including possibly through the car cabin air filter, duct work, and vents.
Symptoms of HPS 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. HPS is serious and people with HPS usually need hospitalization. About one out of three people diagnosed with HPS have died. 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.
How to prevent hantavirus
- Avoid all wild rodents.
- Keep rodents out of your home and workplace by removing their sources of food, water, and shelter and:
- Seal up cracks and gaps in buildings that are larger than ¼” including window and door sills, under sinks around the pipes, in foundations, attics, and any rodent entry hole. Keep food (including pet food) and garbage in thick plastic or metal containers with tight lids.
- Trim trees back and don’t allow plants to grow up alongside your house.
- Stack firewood 18 “ off the ground and away from all buildings.
- If your car has rodents, clean it using the precautions on the next page. Signs of rodents include a foul odor, chewed wires or other components under the hood, and visible nesting material and droppings in the vehicle.
- Trap indoor rodents with snap traps. Place the trap near where you have found droppings. Continue trapping for a week. If no rodents are captured, the active infestation has been eliminated. Also, after a week, any virus in the rodent’s urine/droppings or nesting material could no longer be infectious. Live traps are not recommended because the rodents can continue to urinate and defecate creating more risk of exposure.
- After taking the above steps, clean up rodent infested areas using appropriate precautions.
How to safely clean up after rodents
- Before cleaning, ventilate the space by opening multiple doors and windows for at least 30 minutes to allow fresh air to circulate. Leave the area while it is airing out.
- Wear rubber or plastic gloves and a dust mask.
- Do not vacuum, sweep, shake out rugs or do anything else that may stir up dust.
- Thoroughly spray contaminated areas including trapped mice, droppings, and nests with a mixture of bleach and water: Mix 1½ cups of household bleach in 1 gallon of water (or 1 part bleach to 9 parts water).
- Soak area for 10 minutes, then remove all of the nest material, mice or droppings with a damp paper towel and throw the paper towel in the garbage.
- Mop or sponge the area with bleach solution.
- Wash gloves with disinfectant or soap and water before taking them off. Remove the gloves, then wash hands with soap and water.
- Steam clean or shampoo upholstered furniture and carpets and wash any bedding or clothing in hot water if you see any mouse or rat urine or droppings on them.
How to safely throw out a dead mouse, rat, or rodent nest
- Follow instructions above for wearing and taking off gloves.
- Spray dead rodents and nests with disinfectant and let it soak.
- Seal the dead rodent/nest and all cleaning materials in a bag, then seal that bag in a second bag.
- Throw the bag into a covered trash can.
Stay safe while hiking, camping, or working outdoors
- Do not handle or feed wild rodents!
- Air out cabins and shelters, then check for signs of rodents. 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 thick plastic or metal containers with tight-fitting lids!
- Handle trash according to site restrictions and keep it in rodent-proof containers until thrown away.