Poppagator suggests that this song was written in Ireland, based on letters sent home by Irish worker(s) on the canal in Louisiana. Well, it's a theory, but is there any actual evidence placing this song in Ireland at the relevant time? General anecdotes suggest the song's recent connection with Ireland came about because Christie Moore learned it from the Yorkshireman Mike Waterson, and via Planxty and Paul Brady etc it became extremely widely known. Can we actually place this version(or anything like it) in Ireland say pre-1900? Or even pre-1960?
Also, I am curious Poppagator's equating yellow fever with malaria. They are certainly quite different diseases in British usage, but perhaps the American habit is different?