  We consider the spread of epidemics in technological and social networks. How
do people react? Does awareness and cautious behavior help? We analyze these
questions and present a dynamic model to describe the movement of individuals
and/or their mobile devices in a certain (idealistic) urban environment.
Furthermore, our model incorporates the fact that different locations can
accommodate a different number of people (possibly with their mobile devices),
who may pass the infection to each other. We obtain two main results. First, we
prove that w.r.t. our model at least a small part of the system will remain
uninfected even if no countermeasures are taken. The second result shows that
with certain counteractions in use, which only influence the individuals'
behavior, a prevalent epidemic can be avoided. The results explain possible
courses of a disease, and point out why cost-efficient countermeasures may
reduce the number of total infections from a high percentage of the population
to a negligible fraction.
