Meriwether Lewis's Syphilis

Yesterday on Science Friday Ira Flatow did a program on the flora and fauna that Lewis & Clark brought back from their expedition. None of the guests mentioned one tiny passenger that, according to many Lewis biographers, hitched a ride back home with him and with many of his men: that is, T. Pallidum, the spirochete that causes syphilis. There has been a debate about whether T. Pallidum is plant or animal, which I believe has been settled for now, though I can't remember which won. For those interested in the syphilis hypothesis, read "Trail's End for Meriwether Lewis: The Role of Syphilis," by Reimert Thorolf Ravenholt, "Did Ambrose Bierce Sanitize Meriwether Lewis's Death?", also by Rei Ravenholt, or, if you prefer fiction, the novel Eclipse by Richard S. Wheeler. Tom P. Lowry has a whole book on the topic of the role of syphilis in the Lewis & Clark expedition, currently with a university press, alas, not in time for the bicentennial. I am curious why none of Ira Flatow's guests mentioned syphilis: did they not know of the diagnosis, disagree with it, or feel that it is too shameful to mention? Meriwether Lewis: another historical figure whose hypothesized Pox has been ignored by most writers. What a good question to reopen in this bicentennial year.