Delay Time Models of Population Dynamics with Application to Schistosomiasis Control

Replacing the usual principle of conservation of numbers with the equivalent principle of continuity of flow leads to a very heuristic approach to modeling time lags in population dynamics. The approach allows the direct use of unequal time lags without the implicit assumption of a stable age distribution. It is directly applicable to certain endemic and epidemic diseases. Where time lags occur in the incubation or life cycle of the agent of such a disease, they often importantly affect the dynamics associated with the disease, yet they seldom are accounted for properly.