Rabbit moving in..potential health concerns?

Hi,

My new tenant has a rabbit who is moving into the house. I know there's a potential risk of chinchillas getting diseases from rabbits, but how big is that risk? I'll never allow them to interact, but how far away must they be kept from each other? Can they be kept in the same room?

I wouldn't have them in the same room, unless the room is huge, as in over 100' wide. The bacteria that rabbits can carry that is deadly to chins is transmitted though body fluids. So they have to be far enough away that if the rabbit sneezes or coughs it doesn't reach the chin. Rabbits can carry it without showing symptoms, so even a simple sneeze due to something up it's nose (dust, hay piece, fur) can cause it to spread the bacteria as far as the sneeze travels.
A much better option is to have them in separate rooms, and don't allow play time in the same room or area either. Also wash between touching the rabbit and the chin or any of their cage stuff.