I know your post is a few months old, but I figured it wouldn't hurt to give you my two cents!
As a former employee in the veterinary field, it is crucial that all animals in a household be vaccinated. Although uncommon (Rabies and distemper), your ferrets are STILL at risk of this contagious disease. Most rabies cases are found in raccoons, bats, foxes, any feral animals. It's a misunderstanding that if you do not take your pets outside, they will not get sick... False. You can bring in rabies and distemper through clothing, your shoes, hands, etc. Same for fleas... You could have a flea on your shoe without you even knowing and your pets will have fleas.
You are not entirely safe, but you will be 100% safe if you get your ferrets vaccinated. I completely understand that vaccinating ferrets can be tricky and stressful and I know some vets who do not vaccinate ferrets unless necessary (Multiple animals in the house, outside daily, etc.) as they have a higher level of exposure.
If you choose not to vaccinate, make sure you wash your hands and keep up with proper cleaning and hygiene around your home! If you have multiple animals in the house, especially dogs, I do recommend vaccinations.
<message edited by Raina415 on Tuesday, August 23, 2016 4:49 AM>