[Death Knight][Unholy] Virulent plague vs combat in PvP

[Plaguesynth]

WoW Freakz link: Virulent Plague ,Virulent Eruption
Bug description: Virulent Plague keeping players in combat for the whole duration of it's lasting on the target is posing a problem in PvP currently on freakz. Even tho it's a DoT effect and on some classes as Warlocks and druid their dots didn't keep me in combat for when I wasn't or they weren't attacking . I'm quite unsure but it might be a problem in the DoT itself which I highly doubt or it has something to do with it's Erruption triggering combat. Also when the duration of Virulent was over something still kept me in combat untill I removed my target from the enemy player .
Proof: https://youtube.com/watch?v=9yQc9fqdal4: