Abstract:

An SIS model related to feedback mechanism, crowddensity and crowd moving on sparse distributed regular lattices is proposed. It is shown that  feedback greatly  impacts on the stable infected ratio but does not impact on the spreading threshold of the system. If the spreading efficiency is fixed, the crowddensity is larger and the stable infected ratio is higher. Moreover, there is a crowddensity threshold in this model. Only when the crowddensity is above the threshold,  the disease continuously and steadily spread in a crowd.  The stable infected ratio of a moving crowd is higher than that of a static crowd in the case of low crowddensity, which indicates that the moving activity of individuals can promote the disease spread in the case of low crowd density.

Key words: eedback mechanism; crowd density; crowd moving; SIS model