Well, I was trying to breed a shiny Shinx (Japanese Shinx and English Ditto, I also have a Japanese Ditto and a English Shinx incase the day care guy say's they dont get along), I was checking the summary of my eggs to see how close it was to hatching, and beside the egg it said Pokérus. I was amazed to find Pokerus on my egg that the parents didn't have :D
Hope I helped!