Previous studies reported two Lymnaea snail species (L viridis and L swinhoei) as the intermediate hosts of Fasciola spp. in Vietnam. In this study, the authors investigated in 32 communes of 9 provinces representing for 3 areas of Vietnam for Fasciola cercaria in Lymnaea spp. snails. The authors collected three Lymnaea species, L viridis. L swinhoei and Lymnaea sp.. Of these, L viridis is smallest in size (2-10 mm in length) and mainly living in rice fields with a little water. In contrast, L. swinhoei is large (5-20 mm) with the larger mouth, mainly found in ponds, lakes or rivers
an unidentified species Lymnaea sp. (5-20 mm) has relatively slender and longer whorl, and thrive in clear stagnant or slow-moving water rivers or canals. A total of 43,910 snail individuals, including: 33,510 L. viridis, 9,400 L swinhoei and 1,000 Lymnaea sp. were examined. Fasciola cercariae were found only in L viridis in some sites at very low infection rates (0.06-4.0 percent). A further study on susceptibility of snails to Fasciola larvae and the role of Fasciola transmission of Lymnaea spp. in Vietnam should be carried out.