All those rule books, but it takes just one butt scratch on the way back from the interplanetary probe toilett to unfold this scenario. Poor europe.
Honestly, after seeing those anti-corruption rule books - and on the same homepages where they are displayed, the markers in countrys where you cant to buisness without - sort a contamination scenario in itself, i doubt that anything can prevent this once the dice with the one killing side gets re rolled often enough.
So my money would be on less philosophers employed, more disease-control specialists, which would quickly introduce counter agents that could be consumed by the local flora/fauna.