House mice carry a surprising range of bacteria, viruses, and parasites that can make people sick. A study of mice trapped in New York City apartments found that 37% harbored at least one disease-causing bacterium, and contamination happens easily: a single mouse produces 50 to 75 droppings per day, leaving pathogens on countertops, in pantries, and near food preparation areas. Here’s what you’re actually at risk for and how to protect yourself.
Bacterial Infections From Mouse Droppings
The most common health risk from house mice is bacterial contamination of food and surfaces. When researchers screened over 400 apartment mice, they found gastrointestinal pathogens at notable rates: 14% carried Shigella or invasive E. coli, 12% carried a toxin-producing bacterium that causes food poisoning, 4% carried C. difficile (a stubborn gut infection often linked to hospitals), and 3% carried Salmonella. Among the Salmonella strains identified was the species responsible for the most bacterial food poisoning outbreaks in the United States.
You don’t need direct contact with a mouse to get sick. These bacteria spread through the fecal-oral route, meaning mouse droppings or urine contaminate food, water, or surfaces you later touch. Symptoms typically include diarrhea, nausea, vomiting, and stomach cramps. Most healthy adults recover within a few days, but young children and people with weakened immune systems can develop more severe illness.
Lymphocytic Choriomeningitis Virus (LCMV)
LCMV is a viral infection carried specifically by house mice, and it’s one of the more serious diseases they transmit. You can catch it by breathing in dust contaminated with fresh mouse urine, droppings, or saliva, or through direct contact with nesting materials. The virus can also enter through broken skin, the eyes, nose, or mouth. It does not spread person to person.
Symptoms typically appear 8 to 13 days after exposure and unfold in two phases. The first phase lasts about a week and feels like a bad flu: fever, fatigue, muscle aches, headache, nausea, and loss of appetite. After a brief recovery period, some people enter a second phase involving meningitis (severe headache, fever, stiff neck) or encephalitis (drowsiness, confusion, motor problems like paralysis). In rare cases, LCMV causes inflammation of the spinal cord or heart muscle, or a dangerous buildup of fluid around the brain that requires surgical drainage.
LCMV poses a particular danger during pregnancy. Infection in early pregnancy can cause permanent developmental damage to the fetus, including vision problems and intellectual disability.
Rat-Bite Fever
Despite its name, rat-bite fever is also transmitted by house mice. The bacteria live in rodent saliva, urine, and droppings, and can infect humans through bites, scratches, or accidental ingestion of contaminated material. You can also catch it through broken skin that contacts contaminated surfaces.
The incubation period ranges from 2 days to 3 weeks. Symptoms include fever, headache, skin rash, joint and muscle pain, nausea, vomiting, and diarrhea. The infection responds well to antibiotics, but untreated cases can be fatal roughly 10% of the time, so it’s not something to ignore if you’ve had direct contact with a mouse and develop flu-like symptoms.
Leptospirosis
Leptospirosis is a bacterial infection spread through mouse urine. In the same New York apartment study, researchers detected the bacteria in kidney tissue of 4% of the mice tested. The organism survives in moist environments, so it’s a risk when mouse urine contaminates water sources, damp flooring, or wet surfaces. The bacteria enter through broken skin or mucous membranes. Symptoms range from mild flu-like illness to, in severe cases, kidney damage, liver failure, or meningitis.
Rickettsialpox
Rickettsialpox is a disease you get not from mice directly, but from their mites. A tiny, nearly invisible mite that feeds on house mice can bite humans when mice are living in walls or close quarters. About a week before fever begins, a small raised spot appears at the bite site and develops into a dark scab surrounded by a ring of inflammation. Regional lymph nodes swell. Then comes about a week of intermittent fever with chills, heavy sweating, headache, light sensitivity, and muscle pain. A widespread rash with small blisters appears on the body but spares the palms and soles. The disease is uncomfortable but resolves with treatment, and the scab at the bite site eventually heals with a small scar.
One Disease House Mice Don’t Carry
A common point of confusion: house mice do not carry hantavirus. Hantavirus pulmonary syndrome, the severe respiratory illness you may have heard about in news reports, is carried by deer mice and white-footed mice, which are entirely different species. If you’re dealing with common house mice (the small, gray-brown mice found in walls, kitchens, and basements), hantavirus is not a concern. That said, if you live in a rural area and aren’t sure which species you’re seeing, it’s worth treating any rodent cleanup with the same precautions.
How to Safely Clean Up Mouse Droppings
The single most important rule: never sweep or vacuum mouse droppings dry. Sweeping and vacuuming launch particles into the air, where you can inhale bacteria and viruses. Instead, follow this process:
- Ventilate first. Open doors and windows for 30 minutes before you start. Leave the area during this time.
- Put on gloves. Rubber or plastic gloves are fine.
- Mix a bleach solution. Combine 1.5 cups of household bleach with 1 gallon of water (roughly 1 part bleach to 9 parts water). Mix a fresh batch each time.
- Spray until saturated. Droppings, urine stains, and nesting material should be visibly wet.
- Wait 5 minutes. Let the solution sit so it can inactivate bacteria and viruses before you touch anything.
- Wipe up with paper towels. Place used towels in a sealed trash bag. Mop hard surfaces with the same bleach solution afterward.
- Wash your hands. Wash with soap and water while still wearing gloves, then again after removing them.
Reducing Your Risk
The mice in that New York City study were trapped in ordinary apartment buildings, not unusually dirty ones. House mice thrive anywhere they find food, warmth, and small entry points. Sealing gaps as small as a quarter inch with steel wool or caulk is the most effective long-term prevention, since mice can squeeze through openings roughly the width of a pencil. Store food in hard containers with tight lids, keep counters clean of crumbs, and address any moisture problems that could attract both mice and the bacteria they carry.
If you notice droppings in your kitchen or pantry, discard any food that may have been exposed, even packaged food with gnaw marks. The pathogens in mouse droppings are invisible, and contamination on the outside of a box transfers easily to your hands and then to whatever you eat.