One hundred years of research on the natural infection of freshwater snails by trematode larvae in Europe.

Research on the infection of snails by trematodes has been conducted in Europe for over a hundred years. The initial poor knowledge of the intra-molluscan stages of these parasites together with the difficulty of classifying them constituted a serious obstacle to the undertaking of integrated parasitological and malacological efforts to gain a better understanding of the phenomenon. The compilation of morphological and anatomical results of research on trematode larvae resulted in the publication of keys to designate species of parasites, but was not sufficient to encourage malacologists to collaborate with parasitologists. This paper undertakes to collect data published over the last hundred years on the natural infection of European populations of freshwater snails by trematode larvae. The aim of this undertaking is to make researchers of malacofauna and, above all, experts on freshwater snails aware of the scale of the problem of molluscs being exploited as intermediate hosts of trematodes and, consequently, to encourage parasitologists and malacologists to collaborate on this phenomenon that is crucial for both parasites and hosts.