First, Get Rid of the Source
The first step is to get rid of the rodents completely. Figure out where they are entering the building, and seal up those holes. They say mice can squeeze through a spot as small as a dime, but I've personally seen them slip through barely 1/4 inch slats in vents. So even tiny slits or holes must be repaired. (Not positive what type of pest is leaving behind droppings? This may help.)
You'll also need to set out traps. There are many ways to try to catch rodents, but in my experience, the best is a covered trap set with peanut butter and poison. Of the homemade traps, the type shown here is the best. You may also wish to invest in electronic mouse repellents; we successfully use these. They work well, but you must follow the manufacturer's directions about placing the correct number of them in your building.
Once your traps are free of rodents for seven days, the CDC (Centers for Disease Control) says you can be sure you've caught all the rodents in the area - and that any infectious diseases in the droppings are no longer a danger.
Despite the fact that the CDC says droppings that are 7 days old are no longer likely infectious, they absolutely recommend proceeding as if you can still become ill from them. That means wearing gloves (rubber, latex, or vinyl) and old clothes that you don't mind throwing away - or at least washing in hot water when you're done. The CDC says nothing about wearing a respirator (though this site for professionals says the CDC offers guidelines about them), but many other sources suggest it. Professionals also wear goggles while cleaning up rodent droppings.
Once you have all your gear, open the windows and doors and allow the area to ventilate for 30 minutes before you begin work.
Because so many diseases that infect humans come from the dried up urine dust of rodents, the most important thing is to not stir up dust while you are cleaning. Instead of sweeping or vacuuming, the CDC recommends the following procedure:
1. Spray down areas with droppings or possible urine dust with bleach water (1 part bleach to 10 parts water) or other disinfectant. (This is not the time to use vinegar, folks. Be sure to follow the manufacturer's directions for dilution if using something other than bleach.) Wait 5 minutes.
2. Use paper towels to pick up the droppings. Place the used paper towels in a garbage bag and seal it. Place that bag in another bag and seal it, too.
3. Mop the floor, counters, and other affected surfaces using bleach water or disinfectant. Carpets and upholstered furniture should be steam cleaned, according to the CDC. Clothing, bedding, and the like should be washed with laundry detergent and hot water. If you have boxes of things that are contaminated, take the boxes outside and into direct sunlight; remove everything from the box, staying upwind, so nothing blows into your face. Cardboard boxes must be thrown away, but plastic or metal containers can be disinfected by spraying, waiting 5 minutes, then wiping with paper towels.
4. Remove your gloves and place in a garbage bag. Seal it and place in another garbage bag. Seal that bag, too. Wash hands with hot water and soap for at least 30 seconds before rinsing thoroughly.
If You Find Dead Rodents or Nests
1. Spray with disinfectant. Wait 5 minutes.
2. Wearing your gloves, carefully pick up the rodent or nest and dispose of it in a garbage bag. Seal and place in another garbage bag. Seal that bag, too.
* Title image courtesy of