Modelling parasite density in ruminants

Models of parasite density in ruminants usually involve three nonlinear, coupled, ordinary differential equations for larval density, adult parasite density and host resistance. We deal with the inverse problem of objectively determining the nonlinear coefficients within the equations using available data. Experiments are suggested to allow efficient calculation of these coefficients. An alternative model is also proposed which reproduces key features of experimental results and shows the importance of including time delay equations in parasite modelling.