Figure 3.

Simulated host age–parasite intensity relationships for T. retortaeformis in male rabbits. The basic model is described by the parameters C=35, β=0.001, μ=0.1, δ=0.5, θ=1 for the nematode and θ=0.25 for the worm–virus co-infection. (a–d) explore the effect of changing one parameter while keeping the others constant, specifically changing (a) The strength of the virus-modulated T_H2 response θ, (b) the force of infection parameter C, (c) the immunomodulated establishment–death/expulsion ratio δ and (d) the strength of the total acquired immunity β. The observed mean worm intensity by host age for the nematode (triangles) and virus–nematode co-infection (squares) is reported.