IDdx is a decision support software tool developed by the author of OutbreakID, Dr. Jay Brown. This software is designed to help medical practitioners access information and improve the diagnosis of infectious diseases. Content covers more than 275 communicable diseases indexed by categories and organized in a systematic and unambiguous way. The advantage of IDdx mobile software over a book is that it was built for queries. Users can find specific information by using the disease search criteria, which contains 119 signs & symptoms, 39 epidemiological factors, and covers 16 regions of the world. The user can see all the symptoms associated with a disease or see all the diseases associated with a symptom.