Rodent Contamination, Disease and Damage

Damage from Gnawing
Damage to Home Insulation
Cascade’s Insulation Damage Remediation Services
Rodent Contamination & Disease
Special Hantavirus Section
Dead Animal and Rodent Removal

Introduction – Rats, mice & squirrels can cause significant damage from gnawing various features of a home, auto, or stored items. They also damage insulation causing heat loss. And rodents cause contamination & spread disease. All reasons why you need Cascade to provide rodent extermination & pest control today.

Damage from Gnawing Roofing, Siding, Vents, Plumbing, Wiring & Stored Items – Rodents are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws (Wikipedia) meaning they must gnaw to continually hone down and sharpen their teeth. Rats and mice can gnaw through house siding and some types of roofing. Rats and other rodents cause significant damage to autos and homes by gnawing on wires at great expense. House fires are occasionally attributed to rodents for this reason.

Damage to Home Insulation – Crawl Space and Attic

In crawlspaces beneath homes the insulation is tucked between floor joists just under the floor. Rodents create runways and nests up inside the gap between the insulation and your floor. When that happens the insulation becomes contaminated and matted, so in addition to the filth, the insulation can no longer hold in heat (its “R factor”).

In attics most insulation is the loose, blown-in type. Rats love living in attic insulation because it provides great nesting material and they can burrow into it as it makes them feel safe. The problem is that not only do rats leave copious amounts of droppings and urine that contaminate the attic space but their activity, body weight, and urine compress the insulation greatly, reducing its ability to keep your home warm.

Cascade’s Insulation Damage Remediation Services

Damage remediation is not part of rodent pest management.  Rodents can and may damage insulation and other portions of a home resulting in reduced insulation value (higher heating costs), contamination of parts of home (attic or crawlspace, etc.), and this type of rodent damage or contamination often becomes apparent at the time of sale of a home during the home inspection.   It is for this reason that Cascade urges the client to sooner or later obtain an evaluation of the attic and/or crawlspace by a qualified clean-out/insulation remediation company.

Rodent populations are not static and flair ups can recur causing new damage or contamination after a proper clean out/remediation service—on rare occasions even when rodent pest management measures have been in place.  So, it It is wise to re-check prior to selling home.

Cascade has worked extensively with certain attic and crawlspace clean-out/insulation remediation companies and can provide you with references upon request.

Rodent Contamination and Disease

Contaminated Surfaces
Rats and mice dribble urine and feces wherever they go. This means that even if they haven’t chewed into anything, the surfaces are contaminated.

Contaminated Food
Human and pet food that may have had contact with rodents’ mouths is unfit for consumption.

Rodents are infamous throughout history for spreading disease. Their bites, urine, droppings, dead carcasses, and even mere contact are known to carry a wide variety of bacteria, viruses, and parasites.

Dead Animal and Rodent Removal
Content Coming Soon.

Special Hantavirus Section

Excerpt from WA State Dept. of Health

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.

How are people exposed?

Deer mice excrete the virus in their urine, saliva, and droppings. 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.

Pets, snakes, and predators don’t become infected and can’t spread hantavirus infection to people or other animals.

In North America, there is no evidence that the disease spreads from one person to another.

What are the symptoms of Hantavirus Pulmonary Syndrome?

Symptoms begin one to six weeks after inhaling the virus and typically start with 3-5 days of “flu-like” 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.

Where is hantavirus found and how common is it?

The deer mouse (Peromyscus maniculatus) is the main carrier of hantavirus in the western United States; however, all wild rodents should be avoided. Deer mice live in all parts of Washington, but mainly in rural areas. 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. In Washington, about 14% of over 1,100 tested deer mice have been infected with Sin Nombre virus. Since infected deer mice live throughout the state, human cases of hantavirus pulmonary syndrome can occur in any part of Washington. Typically one to five cases are reported each year.

King County Hantavirus Cases (4/2017)

Seattle/King County Health Dept. Hantavirus Brochure

Seattle/King County Health Dept. advice for homeowners cleaning up where rodents have been in home, sheds, and other buildings.

If you are cleaning out a building that has been closed up, such as a cabin, shed, or garage, or areas where rodent nesting material have been found, follow these steps.

  1. Air out the building for at least 30 minutes by opening windows and doors. Leave the building while it is airing out.
  2. Wear rubber, plastic, or latex gloves. A dust mask may provide some protection against dust, molds, and insulation fibers, but does not protect against viruses.
  3. Mix a solution of 1 cup bleach to 10 cups water or use a household disinfectant
  4. Don’t vacuum, sweep or dry dust areas when cleaning. This disturbs dried rodent urine and feces that may contain harmful bacteria and viruses.
  5. Wet down all contaminated areas, dead rodents, droppings and nesting areas with a disinfectant before cleaning. Allow the disinfectant to set for 10 minutes.
  6. Disinfect counter tops, cabinets and drawers, floors and baseboards.
  7. Steam clean carpets, rugs, and upholstered furniture.
  8. Dispose of dead rodents and contaminated items by double bagging in plastic bags and placing in your garbage can outside.
  9. Wash clothes and bedding in hot water and detergent. Set the dryer on high.
  10. When you are done, disinfect or throw away the gloves you used. Wash your hands or shower with soap and hot water.

Seattle/King County Health Dept. Interim Guidance for Cleaning and Disinfection of Vehicles with Rodent Infestation

Interim Guidance for Cleaning and Disinfection of Vehicles with Rodent Infestations

Rodents, including squirrels, mice, and rats, may construct their nests in cars, trucks, campers, and other vehicles, especially if such vehicles are used infrequently. Rodent nesting materials can be found in many areas of a vehicle:

  • the engine compartment, including in engine compartment insulation
  • the ducting and air filtration components of a vehicle’s heating and air conditioning system
  • the trunk of a car, including the spare tire compartment
  • the passenger compartment, including the headliner, glovebox, and in or under the seats
  • tool compartments
  • taillight and headlight access areas and enclosures

Some rodents, such as deer mice, can carry hantavirus, and their nesting materials, droppings, and urine may contain hantavirus. People who ride in, or clean, the car may come into contact with these infectious materials. Infectious virus particles blowing onto passengers through the air vents may thus pose a risk to people who use the vehicle.

Rodents can enter vehicles through: Rust holes, wire chases, side vents, rocker panels, ducting.

An accumulation of nesting materials in the air intake systems of a vehicle can also contribute to odors inside the passenger compartment and could potentially impair engine performance, preventing the vehicle from starting, or causing it to run poorly. These problems may also be caused by electrical wires and cables that the rodents have chewed on.

Preparing to Inspect, Detect, Disinfect and Remove Potentially Infectious Nesting Materials from a Vehicle

Engine Compartment

While the car is in open air, open the hood to allow the engine compartment to air out for 20 minutes. Also, open vehicle doors and the trunk to facilitate airing out. Wearing plastic gloves and a long-sleeve shirt, inspect the engine compartment for evidence of nest building. Accumulations of nesting materials could occur anywhere, but are frequently found between the battery and vehicle frame, in the area near the window wiper motors, and underneath air intake ducting or within the air filter.

Areas of the vehicle with evidence of rodent activity (e.g., presence of dead rodents, droppings, or nesting materials) should be thoroughly disinfected and cleaned to reduce the likelihood of exposure to hantavirus-contaminated materials.

To avoid generating potentially infectious aerosols, do not use a vacuum cleaner or sweep rodent urine, droppings, or contaminated surfaces until they have been disinfected. Also, do not use “power wash” high-pressure sprayers to soak or dislodge nests or droppings.

First, remove the cables from the battery to reduce the likelihood of getting shocked while cleaning out the nesting material. Then, using either a commercially labeled disinfectant or a mixture of 1 part bleach to 9 parts water, spray the materials until fully soaked and let sit 5 minutes, or follow the manufacturer’s instructions for dilution and disinfection time. Then, use a paper towel to pick up the materials, and dispose of the waste in the garbage. After the rodent droppings and nesting materials have been removed, clean the rest of the area with additional disinfectant. When the recently-sprayed area is dry, re-connect the battery.

Nesting Materials within Automotive Air Intake Systems

Rodents may travel through the vehicle’s air intake system, building nests on top of accordion-style air filters or in hoses and ducting leading directly to the passenger compartment. For engine compartment air filters, open the unit to reveal the filter. If you see evidence of rodent activity, spray as above using either a commercially labeled disinfectant or a mixture of 1 part bleach to 9 parts water. Spray the materials until fully soaked and let sit 5 minutes, or follow the manufacturer’s instructions for dilution and disinfection time. Then, remove both the nesting materials and the air filter, and discard in the garbage. Insert the new replacement filter, and close the unit.

Inspection, disinfection, and possible replacement of hoses, ductwork, other filters, fans, or other components of the system may be necessary if the rodent infestation is extensive, and such work should be carried out by qualified mechanics or automotive professionals, using appropriate precautions. Advise the mechanic of the potential for hantavirus.

Passenger Compartment

Rodents can enter the passenger compartment through ducting, through rusted areas, through areas where cabling passes, and from the trunk. A variety of approaches can be used to seal out holes and cracks where rodents can enter, depending upon the materials available. Do not leave any kind of food anywhere in the car, as it can attract rodents.


Rodents can enter the trunk from holes in the body, through cable conduits, and from the back seats in certain vehicles. A variety of approaches can be used to seal out holes and cracks where rodents can enter, depending upon the materials available. Do not leave any kind of food anywhere in the car, as it can attract rodents.

After Inspection and Cleaning

Before removing your gloves, rinse your gloved hands with disinfectant, pour some disinfectant into the garbage bag containing the disposed material sufficient to soak that materials, and then seal the garbage bag. Rinse your gloved hands with water, remove your gloves, and finish by washing your hands with soap and water.

Prevention of Colonization of Vehicles

Regular exterior and interior inspection of a vehicle, whether in regular use, abandoned, or garaged for the season or otherwise stationary, will help prevent colonization or infestation of a vehicle. Snap traps and poison baits are effective in stopping rodent access into vehicles. When starting a vehicle that has been idle for an extended period, air it out first, and inspect the air intakes and filters before starting the engine.

Note: While there is no way to guarantee the behavior of rodents, including deer mice, Cascade’s periodic service, which includes placement of exterior bait stations can be planned around garages and vehicles parked or stored outdoors to substantially help alleviate infestations.

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