My son was diagnosed at 6 months old. The information that I have read discussed how this is a progressive condition. The more you stay on top of your treatments and care, the easier it is to manage symptoms. I think that before your sister moves forward from this, she should be evaluated by a CF specialist to plan a course of action....then return to her missionary work. I realize this is being written about a month after your posting so I am sure everything I say her has already been said. This is what I appreciate about the forums.