The most charitable thing you can say about "only those with over-active immune systems survived the 14th century plagues" is that it's so broad as to be meaningless. (Might you perhaps have been thinking of Familial Mediterranean Fever?)
Y.pestis is very good at evading the innate immune response (to the point of reproducing inside macrophages and neutrophils) and likes hanging out in lymph nodes. What kind of increased activity would help here?
Y.pestis is very good at evading the innate immune response (to the point of reproducing inside macrophages and neutrophils) and likes hanging out in lymph nodes. What kind of increased activity would help here?