The common house mouse, Mus musculus, is a ubiquitous pest that poses safety and property concerns for humans due to its adaptability and rapid reproduction rate. Mice carry numerous pathogens and inflict damage that can compromise the structural integrity and sanitation of a dwelling. Their presence should be viewed as a health and economic threat requiring prompt mitigation.
Health Risks from Rodent-Borne Pathogens
Mice carry various viruses and bacteria that cause serious illness. One concerning mouse-associated disease is Lymphocytic Choriomeningitis (LCM), a viral infection primarily hosted by the house mouse. LCM often results in mild, flu-like symptoms but can lead to severe neurological illness, including meningitis or encephalitis, in about 15% of symptomatic cases. The virus is particularly dangerous for pregnant women, as infection can transmit to the fetus, potentially causing congenital birth defects or miscarriage.
Another severe threat is Hantavirus Pulmonary Syndrome (HPS), though it is more commonly associated with wild rodents like the deer mouse. Symptoms of HPS begin as non-specific fever and muscle aches but rapidly progress to severe respiratory distress. HPS has a high fatality rate, making potential exposure a serious health concern.
Mice also carry the bacteria responsible for Salmonellosis, a common form of food poisoning causing gastrointestinal distress, fever, and cramping. Furthermore, the Leptospira bacteria, shed in mouse urine, can cause Leptospirosis, an infection that can lead to kidney damage and liver failure if left untreated.
How Mice Contaminate Environments and Spread Illness
The primary mechanism for disease transmission is the contamination of surfaces and air with rodent excreta. Mice continuously shed viruses and bacteria through their urine, feces, and saliva as they move throughout a structure. This contamination affects food preparation surfaces, stored items, and ventilation systems.
The most dangerous route of infection is the inhalation of aerosolized particles. When dried mouse urine or droppings are disturbed, such as by sweeping or vacuuming, the particles become airborne and can be breathed into the lungs. Direct contact also occurs when individuals touch contaminated materials and then touch their mouth, nose, or eyes. Ingestion of food or water tainted by mouse droppings or saliva is a common route for bacterial infections like Salmonellosis and Leptospirosis.
Structural and Property Damage Risks
Beyond the health hazards, mice present significant risks to the physical structure and contents of a building. Mice possess incisor teeth that grow continuously, requiring them to gnaw constantly to keep them filed down. This compulsive chewing behavior targets a wide range of materials within a home.
Electrical wiring is a preferred target, and gnawing through the protective insulation can expose the copper conductor. This exposed wiring creates a fire hazard, with rodents estimated to be responsible for approximately 25% of fires of unknown origin each year. Mice also damage insulation within walls and attics, reducing thermal efficiency and leading to increased heating and cooling costs. Structural damage from rodents, including chewed plumbing and drywall, results in billions of dollars in economic losses annually.
Safe Response to Infestation and Prevention
Addressing a mouse infestation requires specific safety measures to avoid aerosolizing pathogens. Never sweep or vacuum dry droppings or nesting materials, as this action spreads infectious dust into the air. The contaminated area should first be ventilated by opening windows and doors for at least 30 minutes before beginning cleanup.
The proper cleanup procedure involves wearing rubber gloves and thoroughly spraying all droppings and surfaces with a solution of one part household bleach to nine parts water. The solution must soak for at least five minutes to deactivate viruses before the materials are wiped up with disposable paper towels. Once cleanup is complete, all cleaning materials and gloves must be double-bagged and disposed of in a sealed outdoor trash receptacle.
Prevention centers on exclusion and sanitation, beginning with sealing all potential entry points. An adult house mouse can compress its body to squeeze through an opening as small as 6 to 7 millimeters, roughly the width of a pencil. Homeowners should seal cracks in foundations, gaps around utility lines, and any openings larger than a quarter-inch using durable materials like steel wool or caulk. Inside the home, all food, including pet food, must be stored in sturdy, airtight containers made of thick plastic, metal, or glass, as mice can easily chew through cardboard packaging.