Hello...I am just wondering if yellow fever ever relapses, especially due to stress, lack of adequate sleep, nutrition, etc. Also, is mental confusion and loss of memory, cognitive skills, (like cooking,etc) symptoms of this disease and/or its relapse? There is a "friend" who says that this is his case/symptoms, but I am unsure of the truth of this...(says he has had yellow fever before, and now has frequent relapses, w/ above symptoms, etc.)