The priests determined if a disease was spreading. This can be translated in active form. AT: "someone must bring him to the priest" or "he must go to the priest" (See: [[rc://en/ta/man/translate/figs-activepassive]])
Here "raw flesh" could refer to open sores on the skin or it could refer to new skin that has grown, but the area around it is still diseased. Either one indicates that the skin disease is not healing properly.