I'm not sure if "rat bite fever" is the common name for what you're referring to, but I know a couple people on a rat group on FB that got infected after they were bitten. According to them, they now go get antibiotics from the doctor if they are bitten as a precaution to keep from getting it again. If it is caught early, it is very treatable. Other than that, just lots of washing your hands whenever you handle your rodents or their items and try to kill off any wild rats.