You need to find a group health insurance program versus an individual policy. Individual policies can do whatever they want, including applying pre-existing condition clauses or outright refusing to cover you. I would be VERY surprised if you found a private health insurance option that would cover CF.
Nearly half of our family has something that would ding pre-existing. When DH changes jobs, the one major requirement is that the new job has to have decent group health insurance coverage or its absolutley non-negotiable. He just turned down a job offer this summer because the company had group health insurance but the out of pockets difference from our current to the new insurance would have eaten up all but $1K of the pay raise they were offering. Um, no thank you!