Effects of predation on host-pathogen dynamics in SIR models

Area of Science:

• Ecology
• Epidemiology
• Mathematical Biology

Background:

• Infectious disease epidemiology and community ecology are increasingly integrated.
• Previous models (SI) showed predation suppresses disease.
• Recent work (SIR models) indicated immunity can cause a "hump" effect, where low-moderate predation increases disease prevalence.

Purpose of the Study:

• To test the robustness of the "hump" relationship between disease prevalence and predation.
• To examine how realistic ecological factors modify this relationship.

Main Methods:

• Utilized extensions of a basic SIR (Susceptible-Infected-Recovered) model.
• Incorporated factors: density-dependent host regulation, predator saturation, interference, frequency-dependent transmission, predator numerical responses, and resource dynamics.

Main Results:

• A non-monotonic (hump-shaped) relationship between disease prevalence and predation pressure was consistently observed.
• Predator saturation led to complex host abundance dynamics, including bifurcations and potential pathogen extinction at high predation levels.

Conclusions:

• The non-monotonic relationship between predation and disease prevalence is robust across various ecological scenarios.
• Accurate predictions require considering acquired immunity, host regulation, and predator foraging behavior.