Experimental Infection of Lymnaea truncatula and Physa sp. with Liver Flukes (Fasciola sp.)

Abstract

Lymnaea truncatula is one of the oldest snails ever known as intermediate host of Fasciola hepatica in Europe. It has been clarified tha tthe intermediate host present in Japan is L. ollula. Recently, L. truncatula and Physa acuta have been found in the northern and the southwestern part of Japan, respectively. Higashi verified experimentally that the latter might have a role as an intermediate host.
The present authors tried to induce experimental infection with miracidia of liver flukes (Fasciola sp.) in two species of snails, L. truncatula and Physa sp., which had been collected from a stream in Taki County, Hyogo Prefecture, Japan.
L. truncatula was examined for possibility of acting as snail vector for liver flukes. No development of larvae was seen, except an aberrant development which was observed when the snail was exposed to miracidia of liver flukes within 6 or 7 days after the infection. It is clear that the Japanese L. truncatula is identical with no species of snails in Europe from a biological point of view, thouth it is very close to the snail in Europe morphologically.
Experimental infection was carried out twice with a very large number of miracidia of Physa sp. As a result, no development of miracidia or sporocysts was seen in the snail at either time.
The above-mentioned results indicate that no larvae of liver flukes invading L. truncatula and Physa sp. could develop in to rediae or cercariae in the field.