A few mice probably won't hurt you. I work with hundreds if not over a thousand of them in a breeding colony. They are not considered "clean" and have tested positive for heliobactor and mouse norovirus. We just wear masks, gowns, and gloves just in case. We don't have to worry about fleas or any external parasites. Moms often will kill the first litter if they are disturbed or if you change their bedding the day the pups are born. If you found them already blue, they have been left for a long time by mom. Not all mice moms make traditional nests. It is a learned behavior and if the pup grew up with a non nest building mom, they won't build nests themselves unless they shack up with a nest building mom. The official method to putting neonates down is to decapitate if they are 7 days or less.