User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-118.137.140.117-20121214044024/@comment-74.193.211.56-20121214155907

Nah the picture shown is when the hunter gets hit by an infected monster and after that the virus aura surrouding them is dark purple and black. You can see this in the TGS trailer when the infected Tigrex and Goa Magara strike the hunter. I'm sure the photo shown is just Demonization.