Estudio experimental de la biología de los lymnaeidos vectores de la fascioliasis humana y animal
Fascioliasis is a parasitic disease caused by trematodes of two species of Fasciola, F. hepatica and F. gigantica. This distomatosis has always been considered of great veterinary interest due to the losses it causes in husbandry. Moreover, in the last two decades it has proven to be of high public health importance owing to the human endemic areas known in the Latin America, Europe, Africa and Asia, the increasing number of human case reports, the affection of children, and its great pathogenicity in both the acute and chronic phases, including great morbidity, important sequelae and even patient mortality. Of worldwide distribution, this disease is transmitted by gastropod molluscan vectors of the family Lymnaeidae, presenting strict specificity according to each fasciolid causal agent. Recent studies have demonstrated that this disease is very heterogeneous from the transmission and epidemiological points of view, with different transmission patterns and epidemiological situations related to different lymnaeid vector species showing different capacities of transmission to humans and animals, up to a level in which the lymnaeid vectors may be considered as priority markers to assess the local characteristics of the disease, to ascertain its spreading capacity and to design the control measures appropriate for each endemic area. Given the aforementioned applied importance of lymnaeid snails, the present study aims to contribute new knowledge on the biological characteristics of selected lymnaeid species collected in human and animal fascioliasis areas located in different continents. The lymnaeid species studied belong to different groups of the family Lymnaeidae, including vector species of both fasciolid species and related to completely different transmission patterns and epidemiological situations. All aspects have been analyzed in experimental assays made with lymnaeid species cultured in the laboratory under standard conditions, as to allow for significant comparisons. The experimental results obtained are compared with literature data on the same or similar characteristics if available. Among the phenotypic characteristics studied, emphasis has been given to traits showing usefulness for vector species differentiation, fascioliasis transmission capacity and disease spreading power. Additionally, results obtained prove to be of interest for the design of disease control measures at both local and regional levels. Key Words: Fascioliasis, Fasciola hepatica, Fasciola gigantica, humans, livestock, Lymnaeidae, vectors, biological characterization, ethology, selfing, growth, colonization capacity, disease spread.