Durations of disease stages are chosen uniformly at random from a user-specified interval [R low , R high ]. Random numbers, denoted by ξ, on [0, 1] are used to seed the determination of the infected disease stage periods (denoted I Incubation , I Prodromal , I Manifestation , I Chronic ). R low and R high are taken from medical literature and describe a range of days for each stage of an illness. These calculations are simply: (ξ × (R high -R low )) + R low = D, where D is days for a particular stage. (This may be extended in the future to include ability to define a graph to determine the flatness of distribution and the normative peak. This will make a significant difference in modeling of diseases such as rabies, which can, under unusual circumstances, have very long incubations.)