How would hospital records made in April 1862 explain what happened to this soldier at a much later date?
The company roll composed by the commanding officer at the end of 1864 states that Parrish deserted at Dandridge TN on Jan. 16, 1864.
http://www.archives.state.al.us/civilwar/soldier.cfm?id=152974
Note that this record is a transcription of an original roll at the ADAH which may have been quite faded and difficult to read.
The widow's pension application (Mary Ann Parrish, Henry County AL, 1892) should include her statement about his disappearance.