I too see nothing out of the normal in the rate of deaths. Rock Island prison, also in Illinois, sent something over 1000 (thousand) men to the dead house in its first 100 days or so of opening. Other prison camps had worse rates than that.
Rocky, if you want to get a good insight into civil war prison camps and what life was like in them I suggest Portals to Hell: Military Prisons of the Civil War by Lonnie Speers. It is the book I always turn to for information on the P.O.W. camps of both sides.