Not surprising in the least. Rodents, and their fleas, are the primary carriers of Bubonic plague. I'd be more surprised to read that a rodent DIDN'T have some potential pandemic pathogen in its system. Just makes sure to give your pets regular flea baths, especially if you own terriers. Terriers love to hunt and destroy rodents. As well as maintain a good nutritional load. If you're malnourished, you'll get sick more often.