How come she doesn't give the men TB?

In the book she has consumption which is what they called TB back then. It hit her hard because of her lifestyle. In the beginning when she's in the carriage buying flowers with Prudence who is reproaching her for spending too much money she says she's always either too sad or too gay, too nervous, too this, too that, she spends too much money.. basically she's extreme and self indulgent.

Margeurite is a prostitute who lives in the moment but deep down she knows that once her looks are gone she's done. She has no skills other than having affairs with rich men who are infatuated with her because she plays hard to get. It gets harder to play hard to get the harder the face gets. That must have depressed her, made her drink more, party more, spend more, just to distract herself. She wanted to die young.

There was a LOT of TB around in those days, she wasn't the only one who had it. The people in that society were exposed to TB and many other diseases every day, but they weren't going to barricade themselves in their houses to try to keep well! (wouldn't have done any good anyway, one sick servant could have brought the disease in).