Mice carry over 35 diseases that can spread to humans, either directly through contact with their droppings, urine, and saliva, or indirectly through fleas, ticks, and mites that feed on them. Some of these illnesses are mild and self-limiting. Others, like hantavirus, kill more than a third of people who develop severe symptoms. Here’s what you’re actually at risk for and how transmission works.
Diseases Spread Directly by Mice
You don’t need to touch a mouse to get sick from one. Most direct transmission happens when people breathe in dust contaminated with dried mouse urine or droppings, touch contaminated surfaces and then touch their face, or eat food a mouse has gotten into. Bites and scratches can also transmit disease, but that’s less common.
The CDC lists the following among the diseases spread directly by rodents, including mice:
- Hantavirus
- Lymphocytic choriomeningitis (LCM)
- Leptospirosis
- Salmonellosis
- Rat-bite fever
- Tularemia
- Hemorrhagic fever with renal syndrome
Several of these deserve a closer look because they’re either common in the U.S. or particularly dangerous.
Hantavirus: The Most Dangerous Risk
Hantavirus is the disease most people should worry about when they find mice in their home, especially in rural or semi-rural areas of the western United States. The virus lives in mouse urine, droppings, and saliva, and the primary way people catch it is by breathing in tiny particles when dried droppings are disturbed. This is why sweeping or vacuuming mouse droppings is so dangerous.
Early symptoms feel like the flu: fatigue, fever, and muscle aches, particularly in the thighs, hips, and back. About half of patients also experience headaches, dizziness, chills, nausea, vomiting, and abdominal pain. Four to ten days later, the illness takes a sharp turn. The lungs begin filling with fluid, causing coughing, shortness of breath, and tightness in the chest. This stage, called hantavirus pulmonary syndrome, kills about 35% of people who reach it.
Deer mice are the primary carriers in North America, though other wild rodents can also harbor the virus. There is no vaccine and no specific treatment, which makes prevention the only real defense.
Lymphocytic Choriomeningitis (LCM)
An estimated 5% of house mice in the United States carry this virus, and they shed it for their entire lives without ever appearing sick. Like hantavirus, LCM spreads through contact with urine, droppings, saliva, or nesting materials. You can also catch it from a bite.
Most infections cause mild, flu-like symptoms or no symptoms at all. But when the virus reaches the brain or spinal cord, the consequences can be severe. It can cause meningitis (inflammation of the membranes around the brain), encephalitis (inflammation of the brain itself), or both. Symptoms of neurological involvement include drowsiness, confusion, sensory disturbances, and muscle weakness or paralysis. In rare cases, LCM causes a dangerous buildup of fluid in the brain that requires surgical drainage. Permanent nerve deafness and arthritis have also been reported.
LCM is especially dangerous for pregnant women, as the virus can cause severe birth defects.
Leptospirosis
This bacterial infection spreads primarily through water or soil contaminated with mouse urine. Risk spikes after heavy rainfall, flooding, or hurricanes, when contaminated water spreads across wider areas. You can also get infected by directly touching body fluids from an infected mouse, or by eating or drinking something contaminated with their urine.
Symptoms are broad and easy to mistake for other illnesses: fever, body aches, headache, vomiting, diarrhea, chills, fatigue, and stomach pain. Some people develop jaundice (yellowing of the skin and eyes), red eyes, or a rash. Without treatment, leptospirosis can progress to kidney damage, liver failure, or meningitis.
Salmonellosis
Mice naturally carry Salmonella bacteria in their intestines without showing any signs of illness, and they deposit it everywhere they go. Mouse droppings can contaminate countertops, pantry shelves, and food packaging. The bacteria survive several weeks in dry environments and several months in wet ones, so contamination lingers long after the mouse has moved on.
People typically get infected by eating food a mouse has contaminated, or by touching a contaminated surface and then touching their mouth. The resulting illness brings diarrhea, fever, and stomach cramps, usually lasting four to seven days.
Rat-Bite Fever
Despite the name, this infection spreads from mice too. It’s caused by bacteria that live in rodent saliva and can be transmitted through a bite, a scratch, or even handling a mouse. Symptoms typically begin 3 to 10 days after exposure, though they can take up to 21 days to appear.
The illness starts with fever, vomiting, headache, and muscle pain. About half of infected people develop joint pain or swelling. Three out of four develop a distinctive rash on the hands and feet, appearing as flat, reddened areas with small bumps. The rash usually shows up within two to four days after the fever starts. Without antibiotic treatment, the infection can become serious.
Diseases Spread Indirectly Through Parasites
Mice also serve as hosts for fleas, ticks, and mites that can transmit their own set of diseases to humans. You don’t need to see or touch the mouse. A flea that fed on an infected mouse in your attic can end up on your pet or your ankle. The CDC lists these indirect diseases, among others:
- Plague: spread by fleas that have fed on infected rodents
- Lyme disease: spread by ticks that feed on mice during their larval stage
- Flea-borne (murine) typhus: spread by infected fleas
- Tularemia: spread by ticks and deer flies, as well as direct rodent contact
- Babesiosis and anaplasmosis: tick-borne infections linked to rodent hosts
Mice are a critical part of the Lyme disease cycle in the northeastern and upper midwestern U.S. Immature ticks feed on white-footed mice, pick up the Lyme bacteria, and later transmit it to humans. Reducing mouse populations around homes is one strategy for lowering tick infection rates in an area.
How to Safely Clean Up After Mice
The single most important rule: never sweep or vacuum mouse droppings. Sweeping and vacuuming launch tiny virus-containing particles into the air, which is the primary way people catch hantavirus. Instead, follow this process.
Open all doors and windows for at least 30 minutes before you start, and leave the area while it ventilates. When you return, wear rubber or plastic gloves. Mix 1.5 cups of household bleach into 1 gallon of water (a 1:9 ratio) and spray the droppings, urine stains, and nesting materials until they’re thoroughly soaked. Let the solution sit for at least five minutes. Wipe everything up with paper towels, dispose of them in a covered trash can, and then mop or sponge the area with disinfectant.
For heavy infestations, where droppings are widespread or nesting material is piled up, you need more protection: disposable coveralls, rubber boots or shoe covers, protective goggles, and a respirator with a HEPA filter. A standard dust mask is not sufficient for this level of cleanup.
Which Mice Carry Which Diseases
Not all mice pose the same risks. Deer mice, the tan-and-white species common in rural and semi-rural areas across North America, are the primary carriers of hantavirus. House mice, the small gray species that invade homes in urban and suburban settings, are the main reservoir for lymphocytic choriomeningitis. Both species can carry leptospirosis, Salmonella, and rat-bite fever bacteria.
The practical takeaway: any mouse in your home is a health concern regardless of species. You likely won’t identify the species before you’ve already been exposed to whatever it was shedding. Seal entry points, set traps, and clean up evidence of mice using the wet-disinfection method described above. A single mouse produces 50 to 75 droppings per day, so contamination accumulates fast.