Mice: Health Risks, Habits, and Extermination

Medically Reviewed by Jabeen Begum, MD on January 18, 2024
11 min read

Mice are small rodents that are part of the mammal family Muridae. You've probably spotted one before, so you'll recognize their pointy ears, small eyes, whiskers, and long tail. But there are many types of mice that live all around the world, so their looks, behaviors, and habits can vary a lot.

Mice are an important part of the ecosystem. But they can also be pests when they enter your space uninvited, and in some cases, they can even be bad for your health. Here's everything you need to know about mice -- types, habits, health risks, how to know if they're in your house, and how to get rid of them.

Mice aren't usually dangerous, but inside your house they can damage appliances and furniture. They can even cause electrical fires when they gnaw through wires. 

After that, the real danger that most often comes with mice is that they can carry disease. There is a small risk that they can pass it to you and your family members if they: 

  • Bite you
  • Bring ticks, fleas, and mites into your home
  • Contaminate your food and water with their droppings, saliva, and pee
  • Contaminate the dust you breathe in

Mice in the home can spread several diseases:

  • Hantavirus
  • Leptospirosis (bacterial infection)
  • Lymphocytic choriomeningitis (viral infection)
  • Plague (bacterial infection)
  • Typhus (bacterial infection)

Do mice have rabies?

Mice are very unlikely to have rabies and are not known to pass rabies to humans.

Do mice bite?

Mice can bite to defend themselves. But a mouse won’t usually bite you unless you try to catch it. They’re shy and will choose to stay hidden, only coming out when they think you’re not around.

Mice are pretty interesting animals! Did you know that mice talk to each other through ultrasonic vocalizations? This means they make noises that are much higher than you can hear. Another fun fact: The teeth of mice never stop growing. They need to gnaw on things so their teeth don't grow out of control.

Here are a few other things you probably don't know about mice.

Do mice hibernate?

Hibernation is kind of like sleeping. The animal's body shuts down all but the essential processes. Many animals hibernate in winter, such as bears, and some types of frogs, snakes, squirrels, and turtles. Mice don't hibernate. When temperatures drop, they seek shelter to nest, but they're still active and spend much of their time foraging, or searching for food. Often, they enter your home through cracks and crevices and nest in the warmth of walls, attics, and crawl spaces. Outside, mice will burrow into the ground to seek warmth and have babies. 

What do mice eat?

Mice are omnivores, which means they eat both plant and animal matter. When outdoors, they eat a wide variety of fruits, plants, fungi, and insects. Once inside, your home becomes a buffet. They prefer seeds and grains and will also nibble on foods that are high in fat, protein, and sugar. They've been known to eat bacon, chocolate, and butter.

How long do mice live?

Mice live an average of 2.5 years. This depends on where they live. In the wild, they may have shorter lives due to predators. A mouse kept as a pet could live longer if you take good care of it.

Can mice climb walls?

Mice can climb walls, and they are actually quite skilled at it. A brick wall is easy to climb because of the tiny bumps and holes. Concrete may seem flat to you, but a mouse finds tiny porous holes to cling to. Stucco, siding, and wood are also ideal for a mouse’s claws. Glass and smoothly painted walls are harder for a mouse to climb because there’s no place to grip.

There are many species of mice around the world. More than 70 types live throughout the U.S. 

Some common types include:

House mice

House mice are usually gray with cream-colored bellies. Their fur color may vary from light brown to dark gray, though it depends on where the mouse lives. They have four legs and a round body. Their noses are pointed, and their ears are large with little hair. The body of a house mouse is anywhere between 2.5 and 3.75 inches long, while its tail is typically 2.75 to 4 inches long. House mice multiply fast. Each female can have up to 35 babies a year.

Deer mice

Deer mice get their name from the color of their fur -- brown with white feet and a white belly. They are 5-8 inches long with a round body shape. Their tails are noticeable because they are always half brown and half white.

There are more deer mice in the U.S. than any other type of mammal. They mainly live in rural areas because they like fields and forests. Deer mice often live on their own. But when it's mating season, a male and a female deer mouse might share a nest to take care of their young. And in winter, groups of as many as 15 deer mice might share a nest to keep warm.

Deer mice are worrisome because they are the most common carrier of an infectious disease called hantavirus pulmonary syndrome, which can be life-threatening. Although it's rare, you can become sick after breathing in the virus. It can be in the air near the mouse's pee, poop, or saliva. You would have to be very close to it for this to happen.

African pygmy mouse

The tiny African pygmy mouse comes from sub-Saharan Africa and is a popular pet around the world. It's one of the smallest rodents, with a length of 2.5-5.5 inches, including its tail, and it weighs less than 1 ounce. Its coloring is grey to brownish-grey with a pale belly.

Not much is known about their breeding habits, but experts think they have a very limited mating season. Female pygmy mice likely only give birth once a year, and have an average of three babies. Like most mice, they are nocturnal. To avoid the hot African climate, they look for food at night and mostly burrow underground during the day.

Field mouse

The field mouse, also called the wood mouse and the long-tailed field mouse, gets its name from where it likes to live. One of the most common rodents, they make their homes in woods and fields. You may spot them in your garden.

They’re golden brown with a pale underbelly, and their ears and eyes are large in relation to their size. They search for food at night and eat mostly berries and seeds. Females have up to 36 babies a year. What keeps some of their numbers in check are predators such as domestic cats, foxes, and owls.

Normally, mice live outside, where there’s plenty of food. However, they may turn to your house for two main reasons: easy access to food and shelter. Mice know how to look for food and will not pass up the opportunity to eat little bits of food that you drop on the floor. They also do not like cold winter months and will use any crack they can fit through to take shelter in the warmth of your house.

A mouse infestation is not only unpleasant but is also difficult to deal with.

Here’s how to tell whether your house has been invaded by these little rodents:

  • Mouse poop. Mouse droppings look like dark grains of rice about 1/8-1/4 inch in length. 
  • Gnaw marks. Little gnaw marks on household items or food containers are telltale signs that your house may be hosting mice.
  • Footprints. House mice tracks are generally easy to identify. They usually leave four-toed prints with their front feet and five-toed prints with their hind feet.
  • Rub marks. Look for dirty, oily rub marks along a wall where house mice might travel.
  • Odor. When mice live in a particular place in the house, they use it as their toilet as well, so you may notice a distinct smell of house mouse urine. Their fairly strong pee helps mice communicate with each other. A dead mouse can also smell very bad and strong.
  • Runways. If there are many mice in your house, they will use the same route to move from one place to another. These pathways are lined with rub marks, droppings, and footprints.
  • Burrows. Since mice like to burrow, you may find burrows that contain nesting materials.
  • Actual sighting. Normally, a mouse won’t come out if you're around and moving about. Sometimes, however, one will scurry across the floor or some other surface in your presence. This is a sign that there could be more mice hiding somewhere in the house.
  • Damaged items. Mice may nibble on furniture, clothes, wires, and other household items. If they find their way to the places where you store seeds or cereals, mice will definitely eat their fill.

While mice are, in many cases, a nuisance, they're an important part of the ecosystem. They help spread seeds through foraging, which can help support plant habitats. They also serve as food for their predators. Of course, many mice are used in scientific labs to help research diseases. And, many people get joy from having pet mice.

But when they're unwelcome guests in your house, there's not much benefit, and it's a good idea to prevent them from coming in.

If you come into contact with a mouse, immediately wash your hands thoroughly with soap and water. If your clothing came into contact, immediately put it in the washing machine on a hot cycle.

Although they are unlikely to do so, a mouse can bite if threatened. If this happens:

  • Clean the area with soap and warm water.
  • Dry the area and put on some antibiotic ointment and a bandage.
  • Contact your doctor or go to urgent care. You might need an oral antibiotic or a tetanus shot.
  • Watch for signs of infection while the wound is healing, such as skin that feels warmer than usual, redness around the wound, and unusual pain.

To get rid of mice in your house and prevent them from coming back, consider these tips:

  • Have door sweeps installed on exterior doors.
  • Repair all damaged screens.
  • Screen openings to chimneys and vents.
  • Seal all cracks and holes on the outside of the house.
  • Check the areas where utilities and pipes enter the house, and use caulk, steel wool, or a combination of both to seal any spaces.
  • Keep food and other edibles in airtight containers.
  • Throw out trash regularly.
  • Keep attics and basements dry and well-ventilated.
  • Repair pipes and clogged drains.
  • Check items such as boxes, grocery bags, and other packages that are brought into the house.
  • Keep your home and surroundings free of debris and trash.
  • Cut down tree branches and trim back shrubs.
  • Avoid keeping pet food and bird seed outside.
  • Check basements and attics often for signs of mice.

You may want to contact a professional pest control company or contractor. These professionals will have the tools, knowledge, and licenses to remove mice from your home safely.

It might not be possible to permanently get rid of the mice around your property, especially if you live in a rural area. Experts recommend placing safe traps and letting natural predators thrive in the area.

Barn owls, specifically, love to eat mice and are a great addition to rural properties. You can encourage them to stay nearby by creating or buying a nesting box.

How to get rid of mice in the walls

The best way to get mice out of your walls is to make your home less attractive to them. Make sure you

  • Get rid of any food sources.

  • Keep your home clean and tidy.

  • Empty the trash daily.

  • Take away any sources of water by fixing leaks.

Make sure they can't get into the walls in the first place by carefully inspecting any entry points. Mice can squeeze through very small cracks, so don't think something is so small it's not worth filling.

How to keep mice out of your car

Keep mice out of your car by keeping them away from your car. Take the same steps you take to keep them away from your house.

  • Don't park near trash cans or garden areas, where mice are likely to be present.

  • Keep your car in a sealed garage, if possible.

  • Don't store food in the garage (or make sure it's airtight) and get rid of any materials mice can use to make nests, such as old rags, newspapers, and cardboard.

  • Don't leave food wrappers lying around in your car.

How to trap mice

There are a few common types of mouse traps:

  • Snap traps 

  • Electronic traps

  • Glue boards

  • Live traps

Snap traps, electronic traps, and glue boards are not humane. They cause a lot of suffering to animals. You also have to collect the mouse and dispose of it after it's dead, which can be unsafe. Glue boards are especially cruel. The mouse's paws stick to the board, but they do not die. You have to dispose of the mouse while it's still alive, and you could get bitten in the process. As it also causes pain and suffering to the mouse, it may make loud noises while on the glue board.

Pesticide baits are also not a good idea. They are very dangerous for children and pets. Also, if a mouse dies in your wall after eating the bait, it will start to decay and the smell will attract other pests.

Set humane live traps in areas where you find mice droppings or other evidence of mice. Mice tend to run along walls, so set them close to the wall. Check them frequently, because mice can't live for very long in the small space of the trap. When you catch one, immediately put it outside. Make sure you have taken all the steps to prevent them from coming back in again.

Mice repellent

Mice repellents are meant to deter mice from entering your home. Natural substances such as peppermint oil, mothballs, and ammonia and chemical sprays might work by giving off odors that mice don't like. You can put them near places where mice can enter your home. But remember that these substances -- even natural ones -- can be toxic for kids and pets.

Mouse exterminator cost

If you have a lot of mice in your house, you might want to call a professional. The price of the service will depend on your specific problem and where you live. A general estimate is that it could cost anywhere from $200 to $600.