However, before he could ascend fully to his new command, Cathcart contracted yellow fever, a viral infection carried by mosquitoes, which proved fatal. The Cathcart genealogical entry for him states that,"This gallant young officer fell a victim to the yellow fever, at Jamaica, when in command of the Clorinde frigate, with the rank of post-captain, 5th June 1804, in his 22d year, unmarried."[2]