That Little Mouse in Your House is
Even MORE Dangerous Than We Thought!


Those little mice that live in your attic, basement or walls are more than just an annoyance — they carry with them real health threats. The Hantavirus, causes a disease known as Hantavirus Pulmonary Syndrome (HPS) that is fatal in over half of all cases! You can become infected with this deadly disease through contaminated dust from the mice’s droppings, urine and/or saliva in and out of your home.

A Mouse in Your House!

They may look cute, but the not-so-innocent house mouse spreads an airborne allergen that can cause allergies, asthma and more.

But that’s not the only risk that little mouse in your house poses! A study done by researchers at Johns Hopkins Children’s Center and published in the Journal of Allergy and Clinical Immunology found that of 100 inner-city bedrooms of children with asthma, 84 percent had detectable levels of airborne mouse allergen!

Pediatric allergist Elizabeth Matsui, M.D., the lead author of the study, said, “Children living in inner-city homes are continuously exposed to the allergy-causing substance found in mouse urine that is circulating in the air. This exposure increases their risk for developing allergic sensitivity to mice, just as it does for laboratory workers who constantly work with rodents.”

But this isn’t just a problem for inner-city kids; Dr. Matsui points out that previous studies found mouse allergen in about 75 percent of middle-class suburban homes, and a study in the issue of the Journal of Allergy and Clinical Immunology reported that 82 percent of rural, suburban and urban U.S. homes were found to have mouse allergens.

Health Risks of the Not-so-Innocent House Mouse

Mice (and rats) are a serious and very prevalent cause of allergies and asthma. In the case of the Johns Hopkins study, more than 25 percent of the homes tested contained levels of the mouse allergen high enough to aggravate asthma symptoms. Being exposed can lead to:

  • Allergies
  • Asthma symptoms (wheezing, difficulty breathing, etc.)
  • Full-blown asthma attack
  • Asthma-related illnesses

As anyone who suffers from asthma knows, “Because asthma attacks have the potential to be life-threatening, these findings are of some concern,” Dr. Matsui said.

In fact, asthma is so widespread that it affects about 15 million people in the United States. One-third of them are children, which explains why asthma is the leading cause of chronic illness among children, and the third leading cause of hospitalization among those aged 15 years and younger.

Where is the Mouse Allergen Most Likely to Be?

Mouse allergen is found in the mouse urine and dander. It can be anywhere in your home, but researchers with the National Institute of Environmental Health Sciences found that kitchen floors were most likely to have the mouse urinary proteins that can cause allergic and asthmatic reactions. High-rise apartments, mobile homes, duplexes, and triplexes had higher concentrations of the proteins as well.

Mouse allergen appears to be more common in lower-income homes, but certainly is not limited to them. The above researchers noted that 50 percent of homes with household incomes above $60,000 also contained mouse allergens.

Other indicators that mice, and therefore airborne mouse allergen, may be present in your home include:

  • Cracks and holes in walls or doors
  • Open food in the kitchen
  • Evidence of mouse infestation, such as mouse droppings

Get That Mouse Out of Your House

“One of the best ways parents can manage their child’s asthma is to control the home environment and remove any asthma triggers, including mouse allergen,” said Dr. Matsui. You can do this by sealing cracks and holes in doors and walls, properly storing all food, and keeping your home clean at the deepest level possible.

Hantavirus: Is There a Little Mouse in Your House that’s Deadly!


The Not-So-Innocent
Deer Mouse,
Carrier of the
Dangerous Hantavirus

Perhaps we should pay more attention to the great fear of mice that elephants display in cartoons…in particular to the deer mouse and white-footed mouse, both very popular in North America. Despite their cute little whiskers and fuzzy little bodies, the deer mouse and white-footed mouse can be extremely deadly.

But how can such small rodents pack such powerful punches?

The deer mouse and white-footed mouse carry the Hantavirus, which causes a disease known as Hantavirus pulmonary syndrome (HPS). You can become infected from this deadly disease through contaminated dust from the mice’s droppings, urine and/or saliva in and out of your home. Once exposed to the Hantavirus, signs of sickness can take up to five weeks to appear. Initial symptoms are similar to that of the flu:

  • Fever
  • Chills
  • Muscle aches and Pains
  • Nausea and Vomiting

After the initial symptoms, you will start to experience a shortness of breath and coughing. This is an indication that the disease is rapidly progressing and you need to immediately seek hospitalization.

The final stages of the disease result in internal bleeding and respiratory failure. Over half the cases of HPS have resulted in death.

Be Aware of HPS & How to Avoid It, But Don’t Be Scared as a Mouse of It.
For the reason of Hantavirus pulmonary syndrome alone, you are very wise to take commonsense measures to eliminate and keep rodents out of your home. This is especially important during fall and winter, when mice appreciate the shelter and warmth inside your walls as much as you do.

The deer mouse and white-footed mouse are prevalent in North America, but deer mice are particularly concentrated in the western region while the white-footed mouse is concentrated in the northeast.

HPS was first recognized in the U.S. in 1993, while the first confirmed case of HPS in Canada occurred in 1989. Retrospective analysis, however, indicates that HPS has been present in North America since as early as 1959.

While the number of Hantavirus pulmonary syndrome cases is relatively low (you won’t be seeing any alarmist books based on it yet), the severity of the condition – again, it has resulted in death in over half of those who contract it – makes it a true cause for you to take necessary precautions.

To Avoid and Eliminate the Threat of Hantavirus Pulmonary Syndrome

1. Make sure you keep your home, especially your kitchen, at a microsopic level of clean. This includes floors, countertops, appliances, furniture and all home surfaces. But be warned: Common cleaners and cleaning tools like cotton rags and mops do not make the grade in terms of “deep” cleaning to avoid illness. Seriously consider using clothes, mops and other cleaning tools that are made from ultramicrofibers.

2. If you have or have had rodents in your home, the need for cleaning is even more urgent.

    • Keep All Food in Tightly Sealed Containers. This one is self-evident: if mice can get into your food, they will. Whether it is stored in your pantry, cupboards, or refrigerator (mice have definitely found their way inside refrigerators), seal your food so mice and other rodents can’t get inside.
    • Cover Your Garbage with a Tight-Fitting Lid. Garbage cans that mice can easily open (they are remarkably strong) are their fast food joints. Shut down the operation.
    • Don’t Let Your Pet’s Food Remain in Their Bowls for Too Long. Especially if your pet is not going to be in the immediate vicinity of their food for any extended period, toss the food out in a sealed garbage can.
    • Patch Holes in Your Walls Properly to Keep Rodents Out. Use lath screen or lath metal, cement, wire screening or other patching materials, to seal all entry holes that are ¼ an inch wide or wider (both inside and out.)
    • Eliminate Mice in Your Home with Effective Mousetraps!

For those who already suffer from allergies and asthma, actively eliminating rodents, and their urine and dander, is of utmost important for your health. But even if you don’t have any symptoms now, if you suspect mice are in your home, take preventative measures to remove them and their byproducts now. Once you or your children are exposed to mouse allergen, it’s possible that it could lead to allergies and asthma — so please don’t wait to take action until it’s too late.


Johns Hopkins Medicine

CDC Signs and Symptoms for Hantavirus Pulmonary Syndrome

WebMD Hantavirus Pulmonary Syndrome (HPS) Causes, Sympotms

Mayo Clinic-Hantavirus pulmonary syndrome