Skip to main content Accessibility help
×
Home

Mixed strain schistosome infections of snails and the evolution of parasite virulence

  • C. M. DAVIES (a1), E. FAIRBROTHER (a1) and J. P. WEBSTER (a1)

Abstract

Mathematical models often propose that within-host competition between parasites can be a major factor in the evolution of increased parasite virulence. Kin selection predicts that as the coefficient of relatedness between infecting parasites decreases, the benefits of competition to individual genotypes increases. Thus where parasites can adjust their behaviour in response to current conditions, higher virulence is predicted in multiple genotype infections. There is limited experimental data, however, regarding the effects of mixed strain infections on host and parasite fitness. We investigated, for a snail–schistosome system, whether a conditional increase in replication rates occurred in mixed genotype infections and resulted in increased virulence. Four groups of Biomphalaria glabrata snails were exposed to 1 or 2 laboratory strains of Schistosoma mansoni. Mixed genotype infections were observed to be more virulent than single genotype infections, in terms of reductions in host reproductive success and survival. Parasite reproductive rate was also increased in mixed strain groups. Reduced host reproductive success was suggested to be directly due to the genetic heterogeneity of the parasitic infections resulting in increased host defence costs. Reduced host survival was consistent with an adaptive conditional parasite response.

Copyright

Corresponding author

Corresponding author. Tel: +01865 281356. Fax: +01865 310447. E-mail: charlotte.davies@wellcome-epidemiology.oxford.ac.uk

Keywords

Mixed strain schistosome infections of snails and the evolution of parasite virulence

  • C. M. DAVIES (a1), E. FAIRBROTHER (a1) and J. P. WEBSTER (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed