As far as disease-causing germs: very, very few pathogens will survive on a dry surface like a book/ pages to transmit diseases. If the book appears clean and has no visible (or smell-able) mold, and no evidence of insect infestation, it’s fine to touch and handle.

If it’s moldy I would search for an electronic copy and read that. Keep any moldy book away from your other books, as it can spread.

Same with insect-infested books. There may be some helpful techniques for getting rid of them, which you can Google.

However, for a book that’s in the public domain like this one, if you’re worried about it, just get a new paper or electronic copy and read that one.