A scratch from a mouse, whether wild or a pet, requires immediate attention due to the potential for disease transmission. Mice carry pathogens on their claws, fur, and in their saliva that can be introduced directly into a break in the skin. Even a minor scratch is a direct pathway for bacteria and viruses to enter the body.
Immediate First Aid and Wound Care
The immediate step is to thoroughly clean the wound to flush out potential contaminants. Wash the scratched area using mild soap and warm running water for a minimum of five minutes. This extended washing helps mechanically remove microbes introduced by the mouse’s claw or environmental residue.
After cleaning, pat the wound dry with a clean cloth or towel, taking care not to rub the tissue. Apply an antiseptic solution or an over-the-counter antibiotic ointment to eliminate remaining bacteria and create a protective barrier. Cover the scratch with a clean, sterile bandage to shield it from dirt and irritation as it heals. If the wound is a deep puncture or is bleeding profusely, seek immediate medical assessment.
Assessing the Risk of Zoonotic Disease Transmission
A mouse scratch presents a risk because the animal’s claws and fur are often contaminated with urine, feces, or saliva, which harbor infectious agents. One significant bacterial concern is Rat-Bite Fever (RBF), caused by organisms like Streptobacillus moniliformis. RBF is transmitted through bites, scratches, and direct or indirect contact with the rodent’s excretions.
The risk level is influenced by the source of the mouse. Wild mice, such as deer mice, pose a higher risk of carrying pathogens than laboratory or well-maintained pet mice. However, pet mice are not risk-free and can still transmit RBF and the Lymphocytic Choriomeningitis Virus (LCMV). LCMV is a viral infection shed in the urine, feces, and saliva of infected house mice, and transmission occurs when these substances contaminate a scratch.
Hantavirus is associated with wild rodents, but transmission is most commonly through inhaling aerosolized virus from dried droppings, urine, or nesting materials. Since the virus is present in the rodent’s saliva, a scratch or bite from an infected mouse is a potential, though less common, route of transmission. Any break in the skin can introduce common environmental bacteria, making a tetanus booster important if your vaccination status is not current.
Monitoring for Signs of Infection
After initial first aid, closely monitor the wound and your overall health. Localized signs of a bacterial infection include increasing pain, swelling, warmth, and expanding redness at the site of the scratch. The presence of pus or red streaks extending away from the injury toward the heart are serious indicators requiring immediate medical attention.
Systemic symptoms, which suggest a larger infection or the onset of a zoonotic disease like RBF, usually appear within three to ten days after exposure. These symptoms often mimic the flu and include the abrupt onset of fever, chills, and severe headache. Muscle aches and joint pain or swelling are common indicators of RBF.
If the mouse was wild, or if any localized or systemic symptoms develop, contact a healthcare professional immediately. Inform them about the mouse scratch, as this information is important for correct diagnosis and treatment, which typically involves antibiotics for bacterial infections like RBF. Early intervention is important because untreated RBF can lead to complications involving the heart, brain, and lungs.