Ferrets, like most animals are only carriers of tetanus. This means that its harmless to them and they wont have an symptoms. It also means you can't and won't need to cure it. It does mean if you get bitten and havent had a tetanus jab, you should keep an eye on the bite and if it becomes very swollen, you should seek medical advice. Otherwise, i dont think there is a single disease that is transferable from rabbits. Dogs however, are a different case. So if your dog is ill. Keep him away from your stinkers.