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Evolution of virulence: coinfection and propagule production in spore-producing parasites

Curtis M Lively1

  • 1Department of Biology, Indiana University, Bloomington, IN 47405, USA. clively@indiana.edu

BMC Evolutionary Biology
|November 12, 2005
PubMed
Abstract

Insights

Coinfection dynamics influence parasite evolution. Unrelated coinfections increase total parasite production, while related coinfections decrease it, impacting overall virulence.

Area of Science:

  • Evolutionary biology
  • Parasitology
  • Mathematical modeling

Background:

  • Parasite evolution is shaped by a trade-off between reproduction and virulence.
  • Coinfections can alter this trade-off and the parasite's evolutionarily stable strategy (ESS).
  • Models explore how parasite reproductive strategies affect coinfection relatedness and transmission.

Purpose of the Study:

  • To investigate how the number and relatedness of coinfections influence parasite evolution.
  • To model the impact of different transmission functions on parasite reproductive strategies.

Main Methods:

  • A mathematical model was developed to simulate parasite evolution under coinfection scenarios.
  • Transmission success was modeled as a negative-linear or negative-exponential function of total propagules.
  • The effects of increasing unrelated and related coinfections on parasite reproduction were analyzed.

Main Results:

  • Increasing unrelated coinfections decreased parasite reproductive output in the linear model but not the exponential model.
  • Total parasite propagules per host increased with unrelated coinfections in both models.
  • Increased relatedness among coinfections led to reduced parasite reproduction in both models.

Conclusions:

  • Unrelated coinfections can increase overall parasite virulence by increasing infection numbers, not individual parasite aggressiveness.
  • Related coinfections reduce total parasite reproductive output, leading to decreased virulence.
  • Parasite evolution in coinfected hosts is sensitive to the relatedness of coinfecting strains.

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