What is hantavirus?
Hantaviruses are a group of viruses that are carried by rodents. One of them, Sin Nombre virus, is found in deer mice in North America. Sin Nombre virus is the cause of Hantavirus Pulmonary Syndrome (HPS) in people.
Hantavirus in Washington State
Hantavirus-infected deer mice (Peromyscus maniculatus) can excrete the virus in their urine, saliva, and droppings. Infected deer mice live throughout the state and people are at risk for HPS in any part of Washington. Deer mice pass the virus to each other and some of the population is usually infected, but deer mice do not get sick or have any symptoms.
A person may be exposed to hantavirus by breathing contaminated dust after disturbing or cleaning rodent droppings or nests, or by living or working in rodent-infested settings. Typically one to five cases are reported each year and about one out of three people diagnosed with HPS have died.
Hantavirus Cases and Deaths in Washington State
How do I prevent Hantavirus pulmonary syndrome?
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 potential rodent entry point.
- 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. Note that dust mask may provide some protection against dusts encountered during cleaning, but does not protect against viruses.
- 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).
- For more tips on cleaning up rodent debris, visit our rodents page.
What precautions should I use working, hiking, or camping outdoors?
- Avoid coming into contact with rodents and rodent burrows or disturbing dens.
- 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.
How are people commonly exposed?
Any activity that puts you in contact with deer mouse droppings, urine, saliva, or nesting materials can place you at risk for infection. There is no evidence that the disease spreads from one person to another.
Can dogs and cats get hantavirus?
There's evidence that animals, notably dogs and cats can be infected by hantavirus, however they do not get sick or have any symptoms. Dogs and cats are most likely exposed to the virus when preying on infected deer mice. Though dogs and cats can't spread hantavirus directly to other animals or people, they could put people at risk by bringing infected rodents into homes or places where exposure to rodent excretions may occur.
What are the symptoms of Hantavirus Pulmonary Syndrome?
Symptoms begin one to eight weeks after inhaling the virus and typically start with 3-5 days of illness including fever, sore muscles, headaches, nausea, vomiting, and fatigue. As the disease gets worse, it causes shortness of breath due to fluid filled lungs. Hospital care is usually required. It is serious disease and about one out of three people diagnosed with HPS have died.
What should I do if I think I have been exposed to hantavirus?
If you have been exposed to deer mice mice or mice-infested buildings and have symptoms of fever, muscle aches, and severe shortness of breath, see your health care provider immediately. Inform your health care provider of possible deer mouse exposure so that he/she is alerted to the possibility of rodent-borne diseases, such as hantavirus pulmonary syndrome.
What does the deer mouse look like?
The deer mouse is about six inches long from the nose to the tip of its tail. It is grayish to light brown on top, with large ears, a white belly, and a furry tail that is white on the underside. There are many other types of mice in Washington that don't have those features.
How long does hantavirus remain infectious in the environment?
The length of time hantaviruses can remain infectious in the environment is variable and depends on environmental conditions, such as temperature and humidity, whether the virus is indoors or outdoors or exposed to the sun, and even on the mouse's diet (which would affect the chemistry of its urine). The bottom line is that you can't tell how old a dropping is, so all rodent droppings should be handled as if they are infectious. Areas with ongoing rodent infestation are particularly risky and the recommendations for prevention should be followed.
- To learn more about hantavirus in King County, see Public Health-Seattle & King County Hantavirus Pulmonary Syndrome webpage.
- CDC Hantavirus