Stealth vs other spells

Hi, I want to ask something, yes, it does make sense that chaos bane should cancel stealth (should?) because it's just another AOE but what about DKs diseases? When I'm in stealth and DK spreads diseases, I don't get them.

Is it how it should work?

And also, is it just about server latency when I use stealth or vanish and still get charged immediately after that?

I was playing a rogue in PvP only before WotLK, so I'm asking.

Its not dots itself thats breaking your stealth. Its talent Wandering Plague, which have chance (equal to death knights melee critical rating) to proc AOE damage on each Frost Fever and Blood Plague tic to everyone within 8 yards.