Population structure of Toxoplasma gondii: clonal expansion driven by infrequent recombination and selective sweeps

Annu Rev Microbiol. 2008;62:329-51. doi: 10.1146/annurev.micro.62.081307.162925.


Toxoplasma gondii is among the most successful parasites. It is capable of infecting all warm-blooded animals and causing opportunistic disease in humans. T. gondii has a striking clonal population structure consisting of three predominant lineages in North America and Europe. Clonality is associated with the recent emergence of a monomorphic version of Chr1a, which drove a selective genetic sweep within the past 10,000 years. Strains from South America diverged from those in North America some 1-2 mya; recently, however, the monomorphic Chr1a has extended into regions of South America, where it is also associated with clonality. The recent spread of a few dominant lineages has dramatically shaped the population structure of T. gondii and has resulted in most lineages sharing a highly pathogenic nature. Understanding the factors that have shaped the population structure of T. gondii has implications for the emergence and transmission of human pathogens.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Genes, Protozoan
  • Humans
  • North America
  • Phylogeny
  • Polymorphism, Single Nucleotide
  • Recombination, Genetic
  • Selection, Genetic
  • South America
  • Toxoplasma / genetics*
  • Toxoplasma / isolation & purification
  • Toxoplasma / pathogenicity
  • Toxoplasmosis / parasitology
  • Toxoplasmosis / transmission
  • Virulence / genetics