Pokémon Gaming CentralFor topics that aren't necessarily restricted to one game, Pokémon Gaming Central ranges from comparing and contrasting the differences in the gaming generations to discussing the gaming franchise as a whole.
Pokerus is an occurance that is about as rare (or even rarer! count yourself lucky) as encountering a shiny pokemon in the wild. Pokemon in your team get infected by wild pokemon who have the pokerus. It is not based on held items whatsoever.
Congrats on that. :D Since this already got answered, I'll go ahead and close it. Next time you have a question, just use the Q&A thread in the section that corresponds to the game you're playing, in this case it would have been Black and White. :)