Nausea, Vomiting, Diarrhea

Why is there a precipitous drop in vomiting and diarrhea writings around the early 1900's?  Maybe the world was too consumed by recovering from one world war and preparing for another to write about its bowels.

Interestingly, diarrhea as a subject was rarely mentioned until the turn of the century.  In the late 60's and early 70's the subject, like so many taboos, exploded from out of the cramped shadows.

It is hard to have vomiting without nausea, like thunder without lightning, but for some reason nausea is under-appreciated.  Of course vomiting is more drastic and dramatic, and makes for better literature, often cueing the conventional theatrical revelations of pregnancy or displays of severe emotional distress.