Holy respiratory ailments, Batman!
The inside of that old Granville house had been exposed to the elements for years. The walls would be literally crawling with deadly mold and mildew. In fact, when George comes home from his meeting with Potter and stands by the mirror in the bedroom, you can actually see the disgustingness on the wall to the right of the mirror, by the window.
Zuzu wouldn't just have a smidge of temperature, she'd have advanced asthma, as would the rest of the kids. Child Protective Services woulda swooped in and taken all those kids away.
I want the doctor to take your picture so I can look at you from inside as well.