Lorenz ordering of parasite loads across hosts in Isham's model of Host-Macroparasite Interaction

TL;DR

This paper investigates how parasite-induced host mortality affects parasite aggregation in Isham's host-macroparasite model, revealing conditions under which aggregation increases and how mortality rates influence this process.

Contribution

It establishes a Lorenz order framework for parasite loads and analyzes the impact of mortality rates on parasite aggregation in the model.

Findings

Parasite-induced host mortality increases aggregation under log-concave contact distributions.

Mortality rates can have non-monotonic effects on parasite aggregation.

Lorenz ordering provides a quantitative measure of parasite load inequality.

Abstract

In Isham's model of host-macroparasite interaction, parasite-induced host mortality increases parasite aggregation in the sense of the Lorenz order and related measures when the distribution of the number of parasites entering the host at infectious contacts is log-concave. Furthermore, in the presence of parasite-induce host mortality, the rate of parasite mortality may no longer have a monotone effect on aggregation.