The chances of Pokerus generating on a wild or bred Pokemon is 1 to 21,845 in ALL generations of Pokemon, according to Bulbapedia. However, with the release of the Global Trade Station in generation IV, the chances of a traded Pokemon being infected is slightly higher.
It is common courtesy to infect Pokémon to be traded on the Global Trade Station with Pokérus within some parts of the fandom. Also, a Pokémon's chances of being infected with the virus very slightly increase when a Pokémon has been traded from another game.
This, to answer your question, DOES make Pokerus slightly more common in Generation VI only because of trades. Wild Pokemon and your chances of contracting the virus do NOT change.
Hope this helps!