Correction: '214 sent home due to wounds or disease!'
Remember too, that this was decades before the discovery of penicillin. Antibiotics had not been discovered. Back then, diseases such as malaria,, typhus, cholera, and dysentery were common, particularly in military camps in which hygiene was often 'spotty'.
A true perspective of 'disease casualty rates' and the advancement of military medicine and sanitation comes from looking at the numbers and percentages from the Crimean War and the US Civil War, and then WWI and WWII.