It depends on your point of view I guess! Personally, my own worst nightmare is to get a disease like Alzheimers or dementia: the idea of losing control of my mind is terrifying to me. However, I’m sure there are other people who would think that something like cancer or muscular dystrophy or any number of other diseases are worse.
In terms of phobias, I think that’s a tough one: anyone who has a genuine phobia may find it debilitating, but I think ones like agoraphobia (fear of open spaces/public places and crowds) or anthropophobia (fear of people) would be particularly difficult to live with.
I agree with Roisin, the worst disease depends on your perception of it. I think my worst disease would be cancer but that is probably because my mother died of cancer when I was 3 so it’s the disease I fear the most.
I think the worst phobia again depends on the person. If it interferes with the quality of your life and your ability to live life normally then it’s pretty bad! I think phobias which lead to OCD (obsessive compulsive disease) are probably the worst.