http://db.pandawow.me/?spell=45462
Plague Strike among with other abilities should go through cloak of shadows and should apply the diseases on the rogue.
You can see here:
and several blizzard topics regarding cloak of shadows immunities:
https://eu.battle.net/forums/en/wow/topic/3686613265
https://us.battle.net/forums/en/wow/topic/9753835397
http://us.battle.net/wow/en/forum/topic/9628763262
''As such, any debuffs which are applied by physical abilities will still land on you and still be effective.
This includes, as Kazralar mentioned, Blood Plague and Frost Fever (DK's Plague Strike), along with Censure (any Paladin melee attack), Serpent Sting, Black Arrow and Explosive Shot (Hunter)''
Realm: Fun
7/10