We will develop a pioneering methodology to substantially improve the diagnosis of two highly common infectious diseases: group A Streptococcal pharyngitis, and the influenza virus. Our methodology integrates big and rich data from mobile devices and medical records about three critical layers: the individual patient, the general population and the disease dynamics. Outcomes of our study can lead to a breakthrough in the guidelines for detection of these two diseases, and to the establishment of a general framework for computerized decision-support systems for primary care physicians worldwide.