Hi there, I looked up a little about it because my dogs were treated for it about 3 weeks ago. I think the only way humans can get it is through contact with the feces and I imagine any other dog can easily contract it because my vet only took a sample from one of my dogs and told me if one had it, they both would. Mine were treated 2x a day for 5 days, but with a much smaller amount as they are puppies.
I'm sure someone else can fill you in on all the details but from what I understand it's extrememly common for them to get, basically a bacteria that is present and flares up under stress, food changes, etc. I have no idea what symptoms would present in children, but I know diarrhea goes along with it in dogs. Neither us nor our kids had any weird things going on so I assumed we're all fine, and I haven't worried about it.
Good luck getting rid of it!