No, in fact they're pretty hardy animals.  It's always worth knowing
what signs of disease to look for, and every species has common
problems that tend to crop up in elderly individuals, but most ferrets
go for years without even catching a cold.

A lot of the discussion about ferrets on alt.pets.ferrets, rec.pets
and the Ferret Mailing List (FML) [1.3] deals with health problems,
and it's easy to get the incorrect impression that ferrets are
constantly ill.  

As Dr. Bruce Williams, DVM, puts it:

    Ferrets are no more prone to disease than other animals.  However,
    they do have a much shorter lifespan, so these problems come up an
    a more frequent basis.  Plus, most of us own anywhere between two
    and fifteen animals, and many own more than this, or run shelters.
    When you are dealing with such large numbers of animals, you will
    have proportionately more health problems.

    Also, the FML also has several vets that give health advice.  We
    are well known as a place where you can get a prompt response to a
    question about the health of your animal, and several of us also
    are involved with the health care of many of the animals which you
    read about.

    Another thing to consider is that many of the FMLers live in areas
    where vets are not very familiar with ferrets and their diseases,
    so the FML is a good place to get a second opinion or advice for
    their vets.  I field anywhere from 3-8 phone calls daily [9.9] on
    ferret matters from veterinarians around the country.

    Any type of animal that you may obtain as a pet will have
    predisposition to disease.  Ferrets should be expected to get
    diseases of their own, too.  But as most people on the FML will
    tell you, the benefits are far more than the risks.