title: Human and animal Trypanosomes in Côte d'Ivoire form a single breeding population.
abstract: BACKGROUND
  Trypanosoma brucei is the causative agent of African Sleeping Sickness in humans and contributes to the related veterinary disease, Nagana. T. brucei is segregated into three subspecies based on host specificity, geography and pathology. T. b. brucei is limited to animals (excluding some primates) throughout sub-Saharan Africa and is non-infective to humans due to trypanolytic factors found in human serum. T. b. gambiense and T. b. rhodesiense are human infective sub-species. T. b. gambiense is the more prevalent human, causing over 97% of human cases. Study of T. b. gambiense is complicated in that there are two distinct groups delineated by genetics and phenotype. The relationships between the two groups and local T. b. brucei are unclear and may have a bearing on the evolution of the human infectivity traits.
  
  
  RESULTS
  A collection of sympatric T. brucei isolates from Côte d'Ivoire, consisting of T. b. brucei and both groups of T. b. gambiense have previously been categorized by isoenzymes, RFLPs and Blood Incubation Infectivity Tests. These samples were further characterized using the group 1 specific marker, TgSGP, and seven microsatellites. The relationships between the T. b. brucei and T. b. gambiense isolates were determined using principal components analysis, neighbor-joining phylogenetics, STRUCTURE, FST, Hardy-Weinberg equilibrium and linkage disequilibrium.
  
  
  CONCLUSIONS
  Group 1 T. b. gambiense form a clonal genetic group, distinct from group 2 and T. b. brucei, whereas group 2 T. b. gambiense are genetically indistinguishable from local T. b. brucei. There is strong evidence for mating within and between group 2 T. b. gambiense and T. b. brucei. We found no evidence to support the hypothesis that group 2 T. b. gambiense are hybrids of group 1 and T. b. brucei, suggesting that human infectivity has evolved independently in groups 1 and 2 T. b. gambiense.
authors.affiliation: Wellcome Trust Centre for Molecular Parasitology, College of Medical, Veterinary and Biological Sciences, Glasgow, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Capewell
authors.forename: Anneli
authors.initials: A
authors.lastname: Cooper
authors.forename: Craig W
authors.initials: CW
authors.lastname: Duffy
authors.forename: Andy
authors.initials: A
authors.lastname: Tait
authors.forename: C Michael R
authors.initials: CM
authors.lastname: Turner
authors.forename: Wendy
authors.initials: W
authors.lastname: Gibson
authors.forename: Dieter
authors.initials: D
authors.lastname: Mehlitz
authors.forename: Annette
authors.initials: A
authors.lastname: Macleod
mesh_terms: D000818:Animals; D007560:Cote d'Ivoire; D005819:Genetic Markers / Q000235:genetics; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D025341:Principal Component Analysis; D013552:Swine; D014346:Trypanosoma brucei brucei / Q000145:classification / Q000235:genetics*; D014347:Trypanosoma brucei gambiense / Q000145:classification / Q000235:genetics*; D014353:Trypanosomiasis, African / Q000469:parasitology*
chemical_list: D005819:Genetic Markers