The main objective of this paper is to assess the development of electronic disease surveillance systems for detecting infections at the first stages of disease progression (incubation period). This is important not only for the general population but also for vulnerable population groups with special physical needs, defined in this paper as Sensitive Population Groups. Detecting an infection during the incubation period may be critical and could be accomplished by monitoring certain physiology indicators including blood glucose levels, as demonstrated in a recent diabetics' case study. White blood cell count is another indicator of infections that can be easily measured. The bottom-up approach can subsequently be applied for the detection of an outbreak threat. Dedicated electronic disease surveillance systems raise conceptual, organizational, architectural and technological issues that are also highlighted in this paper.