Bats in the belfry – or North Dakota’s McLean County Courthouse –and their poop has seriously sickened at least two employees with histoplasmosis, caused by inhalation of spores from bat guano.

The Bismarck Tribune reports the county has battled a bat problem for years, bringing in specialists to try to seal the old building, trap the bats and remove a thick covering of guano in the courthouse attic.