Jenny, I have a loved one who also has psoriatic arthritis. I understand what you're saying.
But, yuck. I'm a shopper/consumer, not able to diagnose if it's infectious or contagious. If I had the slightest concern about food safety, that consuming what the barista prepared could have ill effects on my health, it is worth mentioning. I wouldn't submit it within the report. I would send my concerns to the scheduler/editor and let them decide if it is info their client should receive.