AN SIRS EPIDEMIOLOGIC MODEL WITH IMMUNITY CAUSED BY LOW-LEVEL OF INFECTION

It has been seen in many epidemic diseases that low level exposure of a susceptible individual to infection of a disease for a certain inter val of time can cause immunity in that individual whereas to transmit infection an exposure to a higher level of infection, viz., number of bites by the infected mosquitoes, number of bacteria, virus etc, durin g that interval is required. In this paper these properties of transmi ssion of a disease have been considered by constructing an SIRS epidem iological model with non-linear incidence rate beta(1)I(p)S(p > 1) for infection and bilinear incidence rate beta(2)IS for causing immunity. The dynamics of the model have been investigated.