An Aspergillosis infection.
Once infected, they have to be careful for the rest of their lives otherwise it would recur. They would have to regularly visit a doctor. It would be fine if it was in the early stages but in severe cases, it would invade the brain and spread to the lungs. The late stages of the infection are fatal.
"You know about this?" Shane was surprised.
"Well, when I was young, my housekeeper contracted this disease because the wooden house he lived in had mold. Everyone's condition is different based on their body. You are so healthy, you shouldn't have been infected."
She's right. In fact, he and Peter didn't stumble into a stream at all. He just wanted to give her an answer she could accept.
So she wouldn't worry about him.
However, Charlotte frowned when she finished speaking. She felt something was suspicious. Shane had such a healthy body, how could he get injured so badly by just running into a stream?