So, I've been reading a lot about quarantine. Primarily, nervous ferrents wanting a new addition and unsure if they should let their established ferts "pick out" the new guy, and/or meet said new guy immediately.
A lot of ferret owners I converse with online do quarantine. The time span is anywhere from 2 weeks to a few months. The foremost reason for this is the risk of ADV (Aleutian's), which is a progressive, ultimately fatal, parvovirus first spread through mink farms and gradually spreading into companion ferrets.
Ferrents who quarantine say they do it until the ferret is proven healthy (usually by means of getting the ADV test results), and then they slowly integrate them within their businesses. It's a noble idea I think. It always is when you think first about safeguarding your animals.
I don't quarantine.
Why don't I? Because ADV can travel on particles as small as dust. So if you bring in a new ferret and keep them in the same house rooms or floors apart, your ferrets could still get infected, IF the new guy is ADV positive. To safeguard appropriately, you would need to house the new guy in a separate house, where you would shower, disinfect each time with a parvocide and change into all new clothing AFTER leaving the new guy's abode.
This is unrealistic in the extreme. Most can't do that. But it's the only 100% safe quarantine.
As for other illnesses, well. There's the threat of earmites, but I generally treat all my guys whenever a new guy is brought in, anyway. My vets automatically include enough for everyone, so that takes care of that (and now that everyone's on oral ivermectin, earmites for my established business is nil). And as for stress related symptoms, I use tummy soothers and affection to try to keep things even. But, any introductions would be stressful. So.
Now, I'm not saying quarantining is bad. Not at all. It's just people can get rabid about it, and try to shame ferrents into following suit, and that's wrong. Especially when it's not guaranteeing anyone's safety.
They have their side. I have mine. As always, how you care for your animals is your choice.