[Mollusc vectors of schistosomiasis in Sardinia and in the Mediterranean area: taxonomy and epidemiology].

The present classification of molluscs, intermediate hosts of Schistosoma in the Mediterranean area (subfamily Bulininae), based on morphological characters of shell, radula teeth and soft anatomy is unsatisfactory. The electrophoretical study of gene-enzyme systems of many strains of different species of genus Bulinus has enabled us in 1979 to split this genus in three well differentiated genera: Bulinus, Physopsis and Isidora (syn. Mandahlbarthia). All the populations of I. truncata at our disposal (from Sardinia, Egypt, Lybia Morocco, etc.) have been genetically studied comparing gene-enzyme systems of each one of them with those of an egyptian reference strain, collected in Giza near Cairo (Egypt). The presence of many genetically well differentiated biotypes has been observed, confirming that Isidora truncata must be regarded as a complex; only in Sardinia have been found 6 genetically differentiated biotypes. The names of the subspecies of Isidora truncata (for instance Isidora truncata, rivularis, etc) have, in our opinion, no taxonomical significance, because it is not possible to identify them morphologically, biologically, serologically, etc. To the contrary the locality of origin of every population of I. truncata complex, followed by the discriminating gene-enzyme systems gives a genetical identification of obvious epidemiological interest.