You beat me to both comments I planned on making after reading this line:

in the English debates regarding the transmission of cholera in the 1840s, less than 5% of scholars supported the idea that cholera was primarily transmitted contagiously. So how could so many doctors and scientists be so wrong?

I see you included The Ghost Map in your bibliography. I can't recommend this enough to anyone interested. It's a great read and it was one of the things which rekindled my love of biology, leading me to grad school.

I was also going to exhort you to talk more more about 'how could they be wrong' in the larger context of science. (It's a theme I've been trying to hit in my own posts.) But then, a few paragraphs later, you get into Kuhn and such.

SO, all I can say is, well done.