Can you share a picture, please? I'm a first timer growing Impatiens (I. balsamina). I've read about the disease in the US from online sources, but I don't think I ever seen it in my part of the world or in person for that matter.

I haven't grown impatiens since 2013...I heard that once the spores are in the ground, you can't plant impatiens there for a number of years. I miss them but they aren't worth the bother if they go into decline a month or two after they're planted. I haven't heard about any new developments in fighting this disease...the garden centres stock these plants because people want them.

I don't think balsamina is effected (?). To the op from the limited description sounds like it could be spider mites on your son's impatiens. If you/he looked closely you would then see fine webbing (like a miniature spider web) on and around the damaged growth. I risked planting a few regular impatiens this year after a couple year absence knock on wood they are thriving.