Mice and humans
Mice have been infesting human houses for thousands of years. They are referred to as European house mice for a reason as they are not native to the Americas. They first noticed us when we settled down and stopped being nomadic. We had more than we could carry on our backs and wanted a place to live that was permanent. We started building towns and cities and even naming them. Rodents quickly followed. They saw that we were storing food for the winter and would infest it and eat it. This started the journey humans have been on for generations: getting rid of mice.
Mice dangers
Mice are dangerous. Not physically, they are not going to bite you or attack you but they bring bacteria and disease into your home as well as insectoid parasites like fleas and ticks. These insects can pass on blood borne diseases that can be permanent and deadly like Lyme disease. Their bodies are covered in dangerous bacteria that they track over your food and home. Their dander can float in the air and be inhaled causing respiratory infections and they are especially dangerous to people who are already ill.
Mice entryways
Mice are adept and finding ways to enter the home. They can squeeze through tiny openings like weep vents and foundation gaps. They can squeeze under door gaps and through holes in siding and brick. They are most likely to enter a home through a back door but they can also make entryways. If your lawn is not trimmed it gives them a place to hide while they naw a hole into your foundation and enter the home. Once they get in they never leave.
Mice feces and urine
Mice feces and urine is a serious danger to the people in the house. An infestation may be treatable but you will be left with a mess that is dangerous to clean up. This mess must be cleaned properly or it will cause infections like hantavirus which can be a serious respiratory illness. If your home smells like urine the job becomes even more difficult. You will need to clean top to bottom but how do you get the feces behind the walls? That would need a professional who can either do a disinfectant fogging of the area which often solves the issue or they can tear down the dry wall and remove the insulation.
Professional disinfection
If you had your house traded for mice by licensed professionals those same professionals can also do the disinfection. They can use shop vacuums with a heap filter to clean the feces, hospital-grade sterilizers to clean the bacteria and even get into the attic and remediate it completely. If you have a mouse infestation try finding a company that does it all because if the same company does the cleaning and the treatment there may be benefits like no inspection fee for the cleaning or having the same technician you liked before doing the rest of the work.