My dog has a couple of patches where his fur is missing and there are bugs crawling around. I have had fleas in my house before and we noticed almost immediately that one of our pets had them. My dog seems to have had these for a while and unfortunately I didn't notice right away, Is it possible that when a dog has fleas they are not bothersome to other pets in the home or the people living in the home?

We had fleas when we first moved into our house, they must have been in the carpet and yard and we didn't notice.
The dogs scratched, but not excessively so I didn't pick up on it until I groomed one of them. We weren't itchy either.

I would get the missing patches of fur checked out by a vet, if he isn't scratching or chewing himself it shouldn't just fall out.

It took me 2 months to fully get rid of the fleas at our place, I had to treat the dogs and all the house and yard and then the next month do it all again before they were completely gone.