title: Phylogeography of Toxoplasma gondii points to a South American origin.
abstract: Toxoplasma gondii, a protozoan found ubiquitously in mammals and birds, is the etiologic agent of toxoplasmosis, a disease causing substantial public health burden worldwide, including about 200,000 new cases of congenital toxoplasmosis each year. Clinical severity has been shown to vary across geographical regions, with South America exhibiting the highest burden. Unfortunately, the drivers of these heterogeneities are still poorly understood, and the geographical origin and historical spread of the pathogen worldwide are currently uncertain. A worldwide sample of 168 T. gondii isolates gathered in 13 populations was sequenced for five fragments of genes (140 single nucleotide polymorphisms from 3153bp per isolate). Phylogeny based on Maximum likelihood methods with estimation of the time to the most recent common ancestor (TMRCA) and geostatistical analyses were performed for inferring the putative origin of T. gondii. We show that extant strains of the pathogen likely evolved from a South American ancestor, around 1.5 million years ago, and reconstruct the subsequent spread of the pathogen worldwide. This emergence is much more recent than the appearance of ancestral T. gondii, believed to have taken place about 11 My ago, and follows the arrival of felids in this part of the world. We posit that an ancestral lineage of T. gondii likely arrived in South America with felids and that the evolution of oral infectivity through carnivorism and the radiation of felids in this region enabled a new strain to outcompete the ancestral lineage and undergo a pandemic radiation.
authors.affiliation: INSERM UMR_S 1094, Neuroépidémiologie Tropicale, Laboratoire de Parasitologie-Mycologie, Faculté de Médecine, Université de Limoges, Limoges 87025, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Bertranpetit
authors.affiliation: MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, United Kingdom.
authors.forename: Thibaut
authors.initials: T
authors.lastname: Jombart
authors.affiliation: Institut des Sciences de l'Évolution, Université Montpellier/CNRS/IRD/EPHE, Place Eugène Bataillon, CC 065, 34095 Montpellier cédex 05, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Paradis
authors.affiliation: Departamento de Medicina Veterinária Preventiva e Saúde Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Hilda
authors.initials: H
authors.lastname: Pena
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
authors.forename: Jitender
authors.initials: J
authors.lastname: Dubey
authors.affiliation: Department of Microbiology, University of Tennessee, Knoxville, TN 37996-0845, USA.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Su
authors.affiliation: INSERM UMR_S 1094, Neuroépidémiologie Tropicale, Laboratoire de Parasitologie-Mycologie, Faculté de Médecine, Université de Limoges, Limoges 87025, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Mercier
authors.affiliation: Univ Lyon, Université Claude Bernard Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive, F-69100 Villeurbanne, France. Electronic address: sebastien.devillard@univ-lyon1.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Devillard
authors.affiliation: INSERM UMR_S 1094, Neuroépidémiologie Tropicale, Laboratoire de Parasitologie-Mycologie, Faculté de Médecine, Université de Limoges, Limoges 87025, France. Electronic address: ajz@unilim.fr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ajzenberg
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000453:epidemiology / Q000469:parasitology*; D002415:Cats; D019143:Evolution, Molecular; D017125:Genes, Protozoan; D049810:Genetic Speciation; D014644:Genetic Variation; D006801:Humans; D010802:Phylogeny; D058974:Phylogeography; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D013020:South America / Q000453:epidemiology; D014122:Toxoplasma / Q000235:genetics*; D014123:Toxoplasmosis / Q000453:epidemiology / Q000469:parasitology; D014124:Toxoplasmosis, Animal / Q000453:epidemiology / Q000469:parasitology*
keywords: Genetic diversity; Maximum likelihood phylogeny; Phylogeography; Time to the most recent common ancestor (TMRCA); Toxoplasma gondii