I know we have bats in our attic. I'm ok with that. They eat the Mosquitos. We have found 2 dead bats in the last few weeks. I've never found dead ones in the 14 years we have lived here. Should I worry about sickness?
There are a few diseases that are active in bats in the US. Of the biggest concern is the possibility of rabies. Very few bats get rabies, but there is still 700 to 800 cases each year in the US. There are a few other diseases that affect bats and cause their deaths. The main thing is to find out what is affecting the bats in your area. Many state animal conservation agencies have web information on the issues affecting bats in their state.
See the Missouri Bat information
White nose disease.
List of state wildlife agencies
Fish & Wildlife Service Bat Disease information.