The disease stages of Figure 11 correspond to the model diagram shown in Figure 1 . One can see that this definition is superior in several ways to what is available with SIRP modeling as shown in the previous section. (See Figure 10 ). In addition to multiple stages, one can define the level of infectiousness for each type of contact that an infected host might have. On the lower right, the partial immunity stage is specified. Here, one is able to define a wide variety of immune responses. Asymptotic decline seems to fit available data and theory on immune system (from left) SIRP Diagram, Multi-city SIRP, Actual versus model Figure 10 (from left) SIRP Diagram, Multi-city SIRP, Actual versus model.