The so-called "body fluid" includes (saliva, blood, love fluid) and so on.
Therefore, even if the patient intentionally does evil and spits on the book, as long as there is no wound on your hand, it will not be infected in theory. -Never have the habit of "turning pages with your fingers dipped in saliva".
Suggestion:
1. Try not to touch those "dirty" or "wrinkled" books.
2. Be sure to pay attention to hygiene, such as washing hands frequently, especially before eating.
3. If you mind, it is recommended to wear gloves and masks.