Division of Environmental Health

Fairfax County, Virginia


TTY 711

10777 Main Street
Fairfax, VA 22030

Pieter A. Sheehan, REHS,
Director, Division of Environmental Health

Rats and Mice

Rodents such as rats and mice can carry harmful diseases. Diseases from these rodents can spread to people through bite wounds, by eating food or water rodents have contaminated, or breathing in dust with their dried urine or droppings that are stirred into the air. People can also get diseases from ticks, mites and fleas that have been feeding on sick rats and mice. The information on this page will help businesses, home owners, renters and pet owners avoid diseases from rodents.

Health Hazards From Rats and Mice

  • They contaminate food and can make people sick.
  • They leave urine and fecal droppings wherever they travel, feed or nest.
  • They can carry more than 200 germs in their saliva, fecal droppings or urine.
  • The protein in their urine can cause allergic reactions in some people.
  • They can cause house fires by gnawing on wires.
  • They can have a litter in 2-5 months and can have up to six litters a year. A pair of rats and their offspring could multiply to 278 rats in one year.

Most Common Rat and Mouse Types in Fairfax County

They are very good at jumping, climbing, swimming, gnawing and squeezing through small openings.  

Common (Norway) Rat

The Norway rat digs and travels through burrows, and will nest underground up to 150 feet from its food supply. It can make a nest in your home by gnawing holes in sheds, walls, etc., or by squeezing through cracks and crevices in foundations, vents, etc.
FACT: Rats can squeeze through an opening as small as a quarter!

House Mouse

The house mouse usually makes a nest in stored materials indoors, but can also live outside, burrowing in areas around fields and lawns. Mice often become a problem in the fall when they enter homes to seek warmth. Mice tend to nest only 10 to 30 feet from their food supply. 
FACT: Mice can squeeze through an opening as small as a nickel!

Signs of Infestation

The most common signs of rats and mice are the evidence they leave behind, such as burrows, fecal droppings, tracks, chewed-out holes in walls, chewed wires, urine stains and nesting materials. You are more likely to see or hear them shortly after dark and in the early morning.

  • Burrows: A burrow is an opening or a hole in the ground about the size of a tennis ball and will be smooth and clean. You may see dirt mounded up where the rat has excavated the burrow. Look for other openings in your home, garage or storage shed that could allow the rats or mice to enter the structure. Seal holes and openings to prevent entry. Mice need only a ¼ inch opening and rats a ½ inch opening to gain entry.
  • Droppings: Droppings are along the path the rodents travel. Droppings should be removed via wet cleaning (soap and water) not dry (broom or vacuum).
  • Runways: Runways are worn paths created by the rodent along its travel route. Rats leave a grease stain on walls and other surfaces of the areas they frequently travel.
  • Gnawing: Gnawing is an early sign of an infestation. Rats often gnaw the bottom of trash receptacles; please be sure to inspect all trash and recycling bins for signs of damage.

Ridding Yourself of Rats and Mice

You must remove their food, shelter and the openings they use to enter your business, home or other buildings. Follow these three steps to control rodents:

  1. Seal up holes or gaps into your home or building to prevent rodents from returning.
  2. Trap rodents by placing traps or bait stations where rodents frequent or travel.  
  3. Clean up their food supply, like garbage in open containers; bird and wildlife feed on the ground; pet waste in the yard.

To learn more about controlling rodents, see Got Mice? Seal, Trap, and Clean Up to Control Rodents.

Consider hiring a Virginia licensed pest management professional who can provide expertise in effectively and safely placing pesticides and traps.

Tips to Minimize Rats and Mice on Your Property

Rats and mice remain in a location and multiply due to availability of food and shelter.

Remove Food

•    Store your  food, bird and lawn/garden seed, and animal/pet feed indoors in containers with tight fitting lids.
•    Clean up spilled food waste and use thick plastic or metal garbage cans with tight lids and no holes.
•    Keep compost bins as far away from the house as possible (100 feet or more is best). 
•    Routinely mix compost piles to encourage rapid decomposition.
•    Pick up dog and animal waste regularly and place in a trash can with a tight fitting lid. 
•    Trim vegetation and don't allow plants to grow up alongside your house.
•    Clean up fallen fruits or nuts from trees.

Limit Shelter

•    Seal up holes or gaps into your home.
•    Keep the area around your home and outbuildings clear of unnecessary storage and debris.
•    Store firewood, lumber, or other bulky items at least 12 inches off the ground and away from your home.

Making a Complaint

If you observe rats and/or mice at a Health Department licensed facility, such as a restaurant or hotel, you may submit a complaint
If you observe rats and/or mice at home, business or other property, please take action to eliminate the rats and/or mice.

The Health Department does not provide pest control treatment. Please contact a Virginia licensed pest control company.


  • Rodents - Centers for Disease Control and Prevention (CDC)