Pokerus is not a status so why should it be displayed as one? Pokemon only can have one status at a time, meaning that if a pokémon was asleep, poisoned, burned, paralyzed or frozen it wouldn't be able to have pokerus, which is not the case. Also, pokerus has only been displayed in the summary screen in the same place as the pokémon's sprite in all the official games.
If you want to show the pokerus in other places you'll have to manually edit the UI's for battle, party and this plugin (maybe some more?) to allow a second "status" to be shown if the pokémon ever catches pokerus as well as add an icon for pokerus yourself.
In any case, since the pokerus only increases EV won in battle, I don't see any reason to go through all this trouble unless you change the way pokerus works and make it affect battles in any negative way for the player (which is the only reason they would be interested in it showing in the party and bag screens).