IDdx is a decision support online tool developed to assist in the diagnosis of infectious diseases. IDdx is like an electronic book that you can query. It is not designed to replace the human mind, but to help the professional with lists and intersections of lists.
For example, one can make a list of all infections that cause abdominal pain and another list of all infections caused by animal bites. The intersection of these two lists is all infections that fit both criteria. This is what IDdx is designed to do - first to do the research to make the lists and then to develop the interface that makes the querying of these lists as easy as possible.
Each finding (signs & symptoms) and epidemiological factor in IDdx requires a lot of research to make these lists as complete and accurate as possible. My method in refining the lists is just plain old iteration, defined by Merriam-Webster as "a procedure in which repetition of a sequence of operations yields results successively closer to a desired result."