title: Lymnaea schirazensis, an overlooked snail distorting fascioliasis data: genotype, phenotype, ecology, worldwide spread, susceptibility, applicability.
abstract: BACKGROUND
  Lymnaeid snails transmit medical and veterinary important trematodiases, mainly fascioliasis. Vector specificity of fasciolid parasites defines disease distribution and characteristics. Different lymnaeid species appear linked to different transmission and epidemiological patterns. Pronounced susceptibility differences to absolute resistance have been described among lymnaeid populations. When assessing disease characteristics in different endemic areas, unexpected results were obtained in studies on lymnaeid susceptibility to Fasciola. We undertook studies to understand this disease transmission heterogeneity.
  
  
  RESULTS
  A ten-year study in Iran, Egypt, Spain, the Dominican Republic, Mexico, Venezuela, Ecuador and Peru, demonstrated that such heterogeneity is not due to susceptibility differences, but to a hitherto overlooked cryptic species, Lymnaea schirazensis, confused with the main vector Galba truncatula and/or other Galba/Fossaria vectors. Nuclear rDNA and mtDNA sequences and phylogenetic reconstruction highlighted an old evolutionary divergence from other Galba/Fossaria species, and a low intraspecific variability suggesting a recent spread from one geographical source. Morphometry, anatomy and egg cluster analyses allowed for phenotypic differentiation. Selfing, egg laying, and habitat characteristics indicated a migration capacity by passive transport. Studies showed that it is not a vector species (n = 8572 field collected, 20 populations): snail finding and penetration by F. hepatica miracidium occur but never lead to cercarial production (n = 338 experimentally infected).
  
  
  CONCLUSIONS
  This species has been distorting fasciolid specificity/susceptibility and fascioliasis geographical distribution data. Hence, a large body of literature on G. truncatula should be revised. Its existence has henceforth to be considered in research. Genetic data on livestock, archeology and history along the 10,000-year post-domestication period explain its wide spread from the Neolithic Fertile Crescent. It is an efficient biomarker for the follow-up of livestock movements, a crucial aspect in fascioliasis emergence. It offers an outstanding laboratory model for genetic studies on susceptibility/resistance in F. hepatica/lymnaeid interaction, a field of applied research with disease control perspectives.
authors: Departamento de Parasitología, Facultad de Farmacia, Universidad de Valencia, Valencia, Spain. M.D.Bargues@uv.es
authors: María Dolores
authors: MD
authors: Bargues
authors: Patricio
authors: P
authors: Artigas
authors: Messaoud
authors: M
authors: Khoubbane
authors: Rosmary
authors: R
authors: Flores
authors: Peter
authors: P
authors: Glöer
authors: Raúl
authors: R
authors: Rojas-García
authors: Keyhan
authors: K
authors: Ashrafi
authors: Gerhard
authors: G
authors: Falkner
authors: Santiago
authors: S
authors: Mas-Coma
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000378:metabolism; D004275:DNA, Ribosomal / Q000378:metabolism; D004463:Ecology / Q000379:methods*; D005838:Genotype; D005843:Geography; D006239:Haplotypes; D007391:International Cooperation; D008195:Lymnaea / Q000235:genetics / Q000502:physiology*; D008957:Models, Genetic; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D015415:Biomarkers; D004272:DNA, Mitochondrial; D004275:DNA, Ribosomal