Can I cure the Sims affected by the Mother Plant w/o playing Strangerville again

I guess this is a "Technical" question but maybe it isn't.   If you have the Strangerville pack and you know the mystery there is affecting sims living in that neighborhood.  But I have started a new game and am not going anywhere near Strangerville.  But I am seeing sims in the other neighborhoods acting like those **bleep** zombie-types and I am not happy.  I suppose I could use the deactivation for that pack but surely it shouldn't bleed over like that if you don't play that pack.  Maybe it is the story progression that sends sims randomly places and they still end up visiting there and whether you actively play that pack or not the plant spores are still "infecting" them?  I was hoping there was a code to just deactivate the game play for that pack without actually removing it because I have heard bad news from people using that new feature.   Also,  if I have sims say living in Oasis Springs and they are jerking around like they are infected will this continue to spread to all my towns and sims?   I would throw my computer out a winidow if that happens  (just kidding of course)