When the weather outside is frightful, it's rodent season: don't let these unwanted "guests" near the door*.

During the colder months, mice and rats pose a constant threat to residential and commercial establishments. Like other mammals, rodents do not enjoy cooler temperatures. Even temperatures as moderate as those in the 40- to 50-degree range can send them in search of a warm nesting place. You can bet that residing at your nursing home--a warm environment with ample food sources and potential shelter from the storms--will be at the top of rodents' wish lists this winter.

Obviously, a rodent infestation can tarnish a nursing home's reputation, but that is just part of the problem. The health of your employees and residents (many of whom have compromised immune systems) is also at serious risk. Rodents and their fleas are carriers of a variety of serious illnesses, including leptospirosis, lymphocytic choriomeningitis (LCMV), hantavirus pulmonary syndrome (HPS), murine typhus, rat-bite fever, rickettsialpox, and salmonellosis.

To keep rodents at bay, review your sanitation program with staff and residents. Pay close attention to areas where food is typically found, such as the kitchen, dining room, nurses' stations, and residents' rooms. Ensure that staff members can recognize evidence of a rodent infestation. Subtle signs of infestation include gnawed electrical wiring, chewed cardboard containers, and droppings. Some reputable pest-management providers will conduct on-site staff training sessions. Here are some additional facts and recommendations to keep your facility rodent-free:

** Rodents like to nibble on leftovers, but paper materials also provide an enticing food source and should be stored in tightly sealed metal or thick plastic containers.

** Eliminate excess water or moisture in and around the facility. While mice absorb enough moisture from their diet, rats require additional water sources to survive. Repair any leaky soft-drink machines, ice machines, and HVAC units. Promptly mop up any puddles in dishwashing areas or around water fountains.

** Trim all vegetation back two to three feet from the side of the building and consider installing a 30"-wide gravel strip around the building's exterior. Because rodents avoid open areas, an exposed buffer can help discourage them from venturing too close to the building.

** Rodents can enter a building through extremely small holes and cracks. In general, if any unintentional opening the size of a pencil eraser is discovered, it is too large and needs to be sealed with a foam sealant or caulking.

** Because rodents do not like the cold, they're likely to invade warm areas such as laundry or boiler rooms (figure 1). Pay close attention to any signs of rodent presence in such places.

** Trash bins provide ample food sources for rodents; they should be placed as far from the building as possible and should be cleaned and rotated regularly.

** When necessary, hire a trained pest-management professional to place tamper-resistant bait stations around the exterior of the building (figure 2). Inquisitive rodents will eat the poisonous bait and die within 48 hours. All bait stations should be closely monitored and documented to track rodent activity for better targeting of future prevention efforts.

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Most of these measures are designed to decrease your facility's appeal to rodents. The bottom line: When it comes to these creatures, it's best to leave them out in the cold.

Frank Meek, BCE, is Technical Director for Orkin, Inc. As a board-certified entomologist and a 19-year industry veteran, he is an acknowledged leader in the field of pest management. For more information, call [phone] or visit www.orkin.com/commercial for a free rodent-prevention consultation. To send your comments to the author and editors, please e-mail [e-mail]. To order reprints in quantities of 100 or more, call [phone].

BY FRANK MEEK, BCE

*This is the latest in a series of seasonal pest-management articles offered by Orkin Commercial Services in Nursing Homes/Long Term Care Management.