Disease is a terrible thing, even in dreams.
A dream about a disease can mean different things depending on the point in the life of the dreamer at which they come up. If you have a dream about a disease when you are getting up there in age then it means that you are worried about what you might come down with in your old age. You are worried that you might get sick and you are starting to be confronted with the idea of your mortality. This happens to young people as well. In fact you don’t have to be 90 years old by any means to have a dream with a disease as the subject matter, but if you do it shows what is on your mind and what you are thinking about. This does not have to be a negative thing at all; it is merely a thing that you should think about. If you have this same dream at a young age it means that you are worried that you might get sick for some reason very soon.
If you have a dream in which your friends are stricken with disease then this could mean that you feel like there is some malignant force which is breaking you apart and which is causing you to go your separate ways despite the close bond that you’ve formed over the years and the closeness which you all enjoy with each other. Perhaps this dream is a sign that you must find out what that terrible thing is and rid yourself of it. Make sure that you and your friends stay as friends. Don’t let anything come in your way like that.