I would write your landlord a letter advising him or her of the rodent infestation and the need to remedy the problem by  acertain date and if not you will contact the local health department about the issue. Keep a copy of the letter for future use and need. If the due date for compliance comes and goes, contact the local health department for an inspection of the unit.If the unit is cited, the landlord will have to remedy the issue within a short period of time.