Fig. 2

Value of post-reproductive hosts under collaboration. A An example epidemic trajectory for \(a=0.2\) displaying the proportions of the three disease states. B Epidemic trajectories for different degrees of collaboration with the younger, potentially reproductive, fraction of the population displayed. C Population growth rate, \(\frac{dN/dt}{N}\), during the epidemic phase (left) and relaxation into endemicity (right). D Comparison of initial, disease free, growth rates and final growth rates at endemic equilibrium. E Equivalent infection death rates for younger, potentially reproductive, hosts resulting in the same growth rate suppression for variable infection death rates among post-reproductive hosts. For strongly collaborative populations the equivalent infection death rate for younger hosts is higher than for post-reproductive hosts