Chicago is a sweet home for a lot of great things – the Cubs, jazz and Blues Brothers come to mind.

But it’s also a hub for pest activity. Just like bed bugs, Chicago finds itself atop Orkin’s list of its top 20 rattiest cities. The markets are ranked by the number of rodent treatments the company performed in 2013.

Here is a look at the top 20 cities for rodent activity:

  1. Chicago
  2. Los Angeles
  3. Washington, D.C. – Hagerstown
  4. New York
  5. San Francisco – Oakland – San Jose
  6. Seattle – Tacoma
  7. Detroit
  8. Cleveland – Akron – Canton, Ohio
  9. Baltimore
  10. Miami – Ft. Lauderdale
  11. Dallas-Ft. Worth
  12. Denver
  13. Houston
  14. Atlanta
  15. Boston – Manchester
  16. Minneapolis – St. Paul, Minn.
  17. Sacramento – Stockton – Modesto, Calif.
  18. Syracuse, N.Y.
  19. Indianapolis, Ind.
  20. Charlotte, N.C.

Even if your city isn’t on the list, now is the time to stand guard. The late fall is a prime time for rats and mice to actively seek food, water and shelter when temperatures drop and winter nears.

It only takes an opening the size of a quarter for a rat to squeeze inside, and a hole the size of a dime for a mouse. Rodents are also known to chew around holes to make them larger, after which they can slip into their chosen overwintering homes – like healthcare facilities.

Rodents depend on humans and their resources to survive. That’s why it is pivotal that your healthcare facility is a rodent-free zone. If proactive steps to prevent rodents aren’t taken, infestations can easily get out of hand.

Should rodents get inside your facility, they could become more than a nuisance. In fact, they can carry hundreds of pathogens that can spread through their urine, droppings and bites. Worse yet, they are also known carriers of deadly neurological and respiratory diseases like lymphocytic choriomeningitis virus (LCMV) and Hantavirus Pulmonary Syndrome. Ticks, mites and fleas can feed on infected rodents and then transmit diseases like pox, plague and typhus indirectly to humans. Additionally, rodents shed their hair twice a year. Because these hairs are protein-based, those who breathe them in may have a negative respiratory reaction.

Not only are rodents tough to control on the outside, but they are very adaptable at living indoors. In fact, some mice that take shelter inside due to weather will never leave and permanently become inside mice – in Chicago, many mice have never seen the outside.

So how do you keep rodents from infesting your facility? A steady cycle of proactive Integrated Pest Management is your best defense. Start by checking for signs of existing rodent activity, including droppings, gnaw marks, rub markings along walls and pipes, or chewed bait in your existing rodent bait stations.

Now is a good time to inspect the exterior of your building for any cracks and crevices that could provide an entry for rats and mice – remember, they don’t need much room to make a hole. Should you find any gaps, seal them with weather-resistant sealant and steel or copper mesh that rodents can’t gnaw through. Also, clean up any standing water or uncovered garbage outside, which could provide rodents with unending nourishment – as well as a reason to stick around.

Cut back any branches and bushes that brush up along your buildings to create a buffer around your facility’s perimeter. As far as entrances are concerned, consider installing two sets of automatic doors and using weather stripping on all doors and windows. Rodents may burrow or live up to 100 yards away from your structure, so your pest management professional should assess the area surrounding your property.

Sanitation measures can give rodents fewer reasons to hang out around your facility. Work with your staff and your pest management professional to go over sanitation guidelines and solutions that can wipe out pest attractants. Also, make sure your staff knows what to do when they spot a pest problem.

By following these steps, you can do your part to help your city stay off this list.

Ron Harrison, Entomologist, Ph.D., is Director of Technical Services for Orkin and an acknowledged leader in the field of pest management.