Heterogeneous hosts: how variation in host size, behaviour and immunity affects parasite aggregation

Area of Science:

• Disease Ecology
• Parasitology
• Amphibian Biology

Background:

• Infection heterogeneity is a fundamental pattern in disease ecology.
• Experimental studies on the drivers of infection heterogeneity are limited.
• Understanding drivers of parasite aggregation is crucial for disease management.

Purpose of the Study:

• To experimentally evaluate the influence of host attributes on infection heterogeneity.
• To assess the roles of host size, behavior, and immunity in parasite aggregation.
• To compare experimental drivers of heterogeneity with natural field observations.

Main Methods:

• Large-scale field assessments of parasite aggregation in Pacific chorus frogs (Pseudacris regilla).
• Laboratory experiments manipulating host immunity (corticosterone) and behavior (anesthesia).
• Analysis using Taylor's Power Law to integrate field and experimental data.

Main Results:

• Infections were consistently aggregated across seven parasite species in natural populations.
• Reduced host immunity or behavior significantly increased parasite loads in isolated hosts.
• Experimental reductions in immunity or behavior amplified infection heterogeneity in groups.

Conclusions:

• Host behavior, particularly, plays a significant role in generating infection heterogeneity.
• Individual host attributes, alongside parasite exposure, influence infection success and aggregation.
• Findings have implications for understanding and managing wildlife and human diseases.