Evolution of pathogen virulence across space during an epidemic
Erik E Osnas1, Paul J Hurtado, Andrew P Dobson
1Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544.
The American Naturalist
|February 13, 2015
Summary
Less virulent pathogen strains spread faster at the epidemic front, while more virulent strains dominate endemic areas. This occurs due to host movement trade-offs impacting pathogen evolution during disease spread.
Area of Science:
- Evolutionary biology
- Epidemiology
- Mathematical modeling
Background:
- Emerging infectious diseases pose significant threats to wildlife and human populations.
- Host movement and pathogen virulence are key factors influencing epidemic dynamics.
- The Mycoplasma gallisepticum invasion in North American house finches provides a relevant case study.
Purpose of the Study:
- To investigate pathogen virulence evolution during epidemic spread.
- To model the impact of host movement trade-offs on pathogen evolution.
- To understand how virulence dynamics change spatially and temporally during an epidemic.
Main Methods:
- Development of a simple, spatially explicit mathematical model.
- Incorporation of host movement reduction and survival trade-offs with pathogen infectiousness.
- Analysis of virulence evolution at the epidemic front versus endemic centers.
Main Results:
- Pathogen virulence is lower at the epidemic front, maximizing wave speed.
- Higher virulence strains prevail in endemic areas, maximizing the basic reproductive ratio.
- Less virulent strains dominate epidemic peripheries, while more virulent strains increase in frequency post-invasion.
Conclusions:
- Host movement trade-offs significantly shape pathogen virulence evolution.
- Virulence dynamics vary spatially, with lower virulence at the front and higher virulence in endemic regions.
- These findings aid in interpreting spatiotemporal epidemic data and understanding transient virulence in emerging diseases.
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