Those Experts™ all started life as egg-spurts just like us. Just do a bit more research and trust your heart and judgment. Generally, the method for disease decisions (epidemiology) is to look up the statistics for your area. You may not even have any Hanta virus cases nearby. And plague is extremely rare. Field rodents aren't as likely to carry disease as city vermin. I wouldn't worry too much about rural squirrels. They are cute and generally eat nuts, not insects. It is far less likely for a squirrel to contract a contagion because the squirrel isn't eating trash like pigeons or rats.