Female ferrets that are not actively breeding should be spayed to prevent serious illness due to estrogen toxicity. Ferrets should be vaccinated annually after their "kit" vaccine series. A rabies vaccine should also be administered on an annual basis. Ferrets are susceptible to heartworm disease and should be put on prevention medication. Ferrets do get fleas. Your veterinarian can suggest a safe flea product to use on your ferret.
Your ferret can catch human influenza. During the flu season, use common sense in avoiding the spread of the flu.
For more information, please read the article Ferret Care