As a Jew myself, I had heard (not knowing for sure if it’s factual) that Jews who ate Kosher food did not get the Bubonic plague. Presumably, this was due to the fact that pork carried the virus of this particular plague. It also might have accounted for the fact that non-Jews were suspicious of why the Jews were not as affected.
Joseph Stalin wanted to regain Russia's (USSR) land that was lost in the previous World War I, (The Great War) basically wanted to take over the world, little by little. To do this, he eliminated anyone who he thought would be more powerful than him, such as the important rulers in the Central Planning Committee.