Someone wrote a photo book about North Brother Island recently. You may have seen pictures in the article at Slate and other coverage:
TL;DR (or trying to avoid spoilers?): executive summary is I didn't like reading a book that was mostly about a non-historical alcoholic turned morphine addict in a codependent relationship with Mary Mallon. Why did I read it at all? Because it was a book group selection in Mayberry, NH (<-- not its real name).
Keane gave Mary Mallon a long-term not-husband, Alfred Briehof. She says she ran across a mention of a gentleman friend in her research, and as near as I can tell, the rest of Alfred is the result of Keane's imagination.
I will expend two sentences on Keane's handling of the historical Mallon. Keane makes no mention that I can see that Mallon didn't really believe in washing her hands -- not exactly an uncommon attitude at the time, but if you are an asymptomatic carrier and the only place you are shedding germs is in your feces [I don't know if this is true, but that is how it is explained to Mary in the book], other people have a Real Strong Interest in how well you wash up. (I read the book very fast, so if you found such a mention and want to share, PLEASE DO! I'll correct this review happily.) Keane presents Mallon's gallbladder as ultimately _not_ the site of infection. And with that, I think we can just proceed to treating this as a purely fictional account.
OKAY TIME FOR ALL YOU SPOILER FEARING FOLK TO DEPART! BOAT IS LEAVING FOR NORTH BROTHER AND IT AIN'T COMING BACK FOR a while or something. Everyone safely gone? Okee.
While some time is spent on Mary's interactions with the families she briefly works with, and her mostly hostile interactions with the people at North Brother, the balance of the book is spent on Alfred. Alfred is an alcoholic, until he gives up on waiting for Mary during her period of quarantine on North Brother Island (I thought about saying first confinement, but that's a term with another meaning in fiction set in this time period and earlier), hooks up with a widow who signs him up for quinine based anti-alcohol therapy and quits. He attempts to get back with Mary (and back on the sauce) but Mary sensibly (mostly because other acquaintance support her in this) gives him the boot. He has a horrible accident with a lamp resulting in severe burns, spends months in hospital and comes out with a morphine addiction that will ultimately kill him. There is a brief side trip to Minnesota, before he returns to NYC to dope and die -- and suck Mary back into his crap. (Mary's judgment is ever terrible; she quite likes dopey Alfred, much more than she liked drinking Alfred.) Mary's efforts to get his body taken care of result in her second capture and quarantine for life, because she had been baking and cooking including at a maternity hospital and killed a bunch more people.
Mary is fairly unpleasant, but a book about Mary as Keane wrote her, with a touch more about what the medical-scientific side of the case knew and thought, would have been interesting and memorable. Because the book is as much or more about Alfred as it is about Mary, it is instead about a co-dependent spiral into death and destruction in a poverty stricken city with a whole lot of collateral damage. It's a quick read, and that's about the only good thing I can say about it.