Is parkinsons considered a pre-existing illness?

Assuming that you had treatment for it in the six months before you join the new plan, yes it is a pre-existing illness. That doesn't mean that the new plan can refuse to pay claims for your treatment. If you had continuous coverage -- meaning no lapses in your health insurance, or a lapse of less than 63 days -- then the new plan will cover all of your bills for parkinsons.

In 2014, all plans will cover pre-existing conditions regardless of your past plans.