> One of the rare examples of a mental health condition being virtually completely eliminated is that of General paresis of the insane, a symptom of late-stage syphilis.
I think a better example is the very recent (i.e., in the 2000s) discovery of anti-NMDAR encephalitis which can very closely resemble schizophrenia [1].
In syphilis, there were at least other manifestations of disease that can (and were) known, unlike this totally unappreciated mechanism (which better resembles Barry Marshall and H. pylori).