This is the original version of my answer to this prompt by u/RealityScribe:
There are five fatal illnesses discovered across the world. Each only may infect only one person at a time and until the illness takes the life of the afflicted, nothing else can kill them. To your horror and amazement, two of them have chosen you as their host, and neither can run their course.
I made an improved version 5 days after this one which can be found here.
It was finally on the news; two of the Illnesses hadn’t been sighted in months.
This had happened before of course, but in this day and age, where almost everyone was connected to the internet, it was still a newsworthy event.
The last time had been when The Runner was plaguing a small village in some rainforest, and The Fever had infected some poor monastery up high in the mountains. Back then, people had talked about the Illnesses being gone for good, only to be disappointed not long after.
This time… Edward wasn’t sure if they would.
He’d been able to hide the symptoms for so long, only because they hadn’t worsened the way they usually would. He blamed his running nose on crying, and disguised his coughs as clearing his throat. So far, he hadn’t been reported by anyone, and he was going to keep it that way. If anyone else found out he was infected with not just one, but two of the Illnesses… He didn’t want to know what they would do.
Nothing else could kill you while infected with one of the Illnesses. Never before had someone tested the Illnesses against each other. The symptoms of neither were progressing at all. They stayed at the beginning stages, never doing him any actual harm. Edward was functionally immortal. But that wouldn’t be a good thing if anyone found out.
So Edward made peace with being known as the weirdo with the eternal teary eyes and incessant need to clear his throat. It was better than being used for immortality experiments by the Healers. He wouldn’t be the first infected to disappear before the Illness took him.