Some people own rats or other rodents. In fact, they can make a great pet, especially if you invest the time to "trust train" them. This is a process of letting them have an area to roam free around you, and requiring the rodents to eat from your hand. But rodents will be rodents, so make sure they don't have a place to hide under or a nice piece of sheetrock to chew through.
Pet rodents are bathed, well fed, and kept in cages most of the time. They don't generally bite, and if they do, you don't have to worry about getting rabies. For these reasons they are not a danger in your home.
A pest rodent like a rat or mouse is another animal altogether. Let's break this down and look at the differences between the two, using the pet rats positives as our guide.
Pet rodents are bathed. A pest rat grooms itself more than a cat. But this grooming slows or stops altogether if it gets sick. Though it has a robust gastrointestinal tract, the dirty places it forages through can be filled with bacteria and disease.
Pet rodents are well fed. A nutrient deficient rodent is a desperate forager and less choosy about what it eats. This can put bacteria in its belly, and eventually in its droppings and urine. Inside a home, a rat or mouse can contaminate shelves, counters, and food products, with their feces and urine. Also, a hungry rodent will chew through cardboard and paper containers to get at their contents.
Pet rodents are kept in cages. It is never a good idea to have a rodent running around your house. Rodents chew wood, wallpaper, sheetrock, and wires--which makes them a potential fire hazard. These pests can also come and go from a home as they please if they find entry points. This allows them to bring bacteria and parasites into your home.
Pet rodents don't generally bite. Pest rodents don't generally bite either. If they hear you coming, they will probably run away. But there are conditions that can cause rats or mice to bite: if they are sick with rabies, cornered, or scared. It is always best to get a pest professional to deal with a rodent infestation.
So in conclusion, if you want rats or other rodents in your home, get a domesticated one from the pet store. But if your home has pest rodents in it, call a professional to safely remove them, clean the infected areas, and seal your exterior walls from future entry. Rodents can be a serious threat to your home and your family. It is never worth the risk.