Lymnaea schirazensis, an Overlooked Snail Distorting Fascioliasis Data: Genotype, Phenotype, Ecology, Worldwide Spread, Susceptibility, Applicability

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. METHODOLOGY/PRINCIPAL FINDINGS: 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/SIGNIFICANCE: 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

Alpine Crossroads or Origin of Genetic Diversity? Comparative Phylogeography of Two Sympatric Microgastropod Species

The Alpine Region, constituting the Alps and the Dinaric Alps, has played a major role in the formation of current patterns of biodiversity either as a contact zone of postglacial expanding lineages or as the origin of genetic diversity. In our study, we tested these hypotheses for two widespread, sympatric microgastropod taxa – Carychium minimum O.F. Müller, 1774 and Carychium tridentatum (Risso, 1826) (Gastropoda, Eupulmonata, Carychiidae) – by using COI sequence data and species potential distribution models analyzed in a statistical phylogeographical framework. Additionally, we examined disjunct transatlantic populations of those taxa from the Azores and North America. In general, both Carychium taxa demonstrate a genetic structure composed of several differentiated haplotype lineages most likely resulting from allopatric diversification in isolated refugial areas during the Pleistocene glacial periods. However, the genetic structure of Carychium minimum is more pronounced, which can be attributed to ecological constraints relating to habitat proximity to permanent bodies of water. For most of the Carychium lineages, the broader Alpine Region was identified as the likely origin of genetic diversity. Several lineages are endemic to the broader Alpine Region whereas a single lineage per species underwent a postglacial expansion to (re)colonize previously unsuitable habitats, e.g. in Northern Europe. The source populations of those expanding lineages can be traced back to the Eastern and Western Alps. Consequently, we identify the Alpine Region as a significant ‘hot-spot’ for the formation of genetic diversity within European Carychium lineages. Passive dispersal via anthropogenic means best explains the presence of transatlantic European Carychium populations on the Azores and in North America. We conclude that passive (anthropogenic) transport could mislead the interpretation of observed phylogeographical patterns in general

Croissance de la stature et du poids d'écoliers âgés de 6 à 17 ans de la ville de Mostaganem, Algérie occidentale

HEIGHT AND WEIGHT GROWTH OF SCHOOLCHILDREN AGED 6 TO 17 YEARS IN THE CITY OF MOSTAGANEM, WESTERN ALGERIA Summary. — Analysis of height and weight growth of 5 1 3 boys and 602 girls indicates irregularities, with slowdowns and marked accelerations, especially among girls. Comparison with North African and Mediterranean series shows different patterns of growth and often dissimilar yearly increments. Irregular growth process of the children in Mostaganem may be attributed to unfavourable environmental conditions, especially malnutrition due to a low income and high cost of living.Résumé. — L'analyse de la croissance de la stature et du poids de 513 garçons et 602 filles indique des irrégularités, avec des ralentissements et de fortes poussées, notamment chez les filles. Une comparaison avec des séries du Nord de l'Afrique et de l'Europe méditerranéenne montre des modes de croissance différents et des accroissements annuels rarement comparables. Le déroulement irrégulier de la croissance des enfants de Mostaganem pourrait être attribué à des conditions de vie peu favorables caractérisées notamment par une alimentation mal équilibrée due à des revenus trop bas par rapport au coût élevé de la vie.Chamla M-C., Bourguignat H., Bourguignat S. Croissance de la stature et du poids d'écoliers âgés de 6 à 17 ans de la ville de Mostaganem, Algérie occidentale. In: Bulletins et Mémoires de la Société d'anthropologie de Paris, XIV° Série. Tome 2 fascicule 2-3, 1985. pp. 157-180