The term,"Dibilitus" was listed on my ancestors service record from the Nat.Archives when he was admitted for 3 months to the Petersburg Hospital after Camp Douglas.I would assume it was a catch-all phrase to mean debilitated somehow from whatever he may have caught.In the 1930s a son had written that he died from a fever and since his wife died 3 days before he did I can only assume again that she caught it.
I agree it is doubtfull that the Confederate Military would have notified any families of the soldiers return from the exchange.If able,the soldiers would have written personal letters.Many were also,if able,sent to an exchange camp for reorganization or back to their unit if it was intact.
I would speculate that all seriously ill soldiers would have been taken to a Vicksburg hospital or sent to another in Mississippi or sent home if not too ill or perhaps debilitated.
It is also probable that if paper was available the Vicksburg newspaper may have printed the names of exchanged soldiers and other papers throughout the south would have done the same.Many families would have learned the fate of their soldier from those papers.I do not know how many of the Vicksburg papers survived the war.Ive heard of a few printed on wallpaper during the siege.
Have you gotten his service record yet?