If you have multiple terrariums it is advisable to wash your hands properly between two terrariums during the work.
Do this after every terrarium when you want to be as safe as possible.
I know it is a lot of work when you have many terrariums.
When you suspect that one of the snakes is ill or when you have new snakes, take care of these terrariums/snakes as last in the row.
After taking care of an ill snake, disinfect your hands with alcohol or wear disposable gloves.
When I don’t trust something I always use disposable gloves.
The best sequence between your terrariums is to take care for the animals (if possible) in order of purchase.
The last snake that you purchased Is handled as (second-)last snake you take care of. The ill snakes are completely at the end of the row, the quarantine part.
All this seems excessive and “a lot of work”, but trust me, once you have an outbreak of, for example snake-mites in all your terrariums, then you have much, much, much more work!
When you have a stable group of snakes and no recent purchases, the washing of your hands between every terrarium is not really necessary. But if you want to play it safe, you can not be too careful.
Take a look at this page for some more info about treating diseases.