Morphological and Molecular Characterization of Lymnaeid Snails and Their Potential Role in Transmission of Fasciola spp. in Vietnam

Freshwater snails of the family Lymnaeidae play an important role in the transmission of fascioliasis worldwide. In Vietnam, 2 common lymnaeid species, Lymnaea swinhoei and Lymnaea viridis, can be recognized on the basis of morphology, and a third species, Lymnaea sp., is known to exist. Recent studies have raised controversy about their role in transmission of Fasciola spp. because of confusion in identification of the snail hosts. The aim of this study is, therefore, to clarify the identities of lymnaeid snails in Vietnam by a combination of morphological and molecular approaches. The molecular analyses using the second internal transcribed spacer (ITS2) of the nuclear ribosomal DNA clearly showed that lymnaeids in Vietnam include 3 species, Austropeplea viridis (morphologically identified as L. viridis), Radix auricularia (morphologically identified as L. swinhoei) and Radix rubiginosa (morphologically identified as Lymnaea sp.). R. rubiginosa is a new record for Vietnam. Among them, only A. viridis was found to be infected with Fasciola spp. These results provide a new insight into lymnaeid snails in Vietnam. Identification of lymnaeid snails in Vietnam and their role in the liver fluke transmission should be further investigated.

DNA identification of Fasciola SPP.on human and cattle in central Vietnam

Macroscopic observation of 1350 Fasciola collected from human and cattle in Binhdinh and Khanhhoa provinces identified three morphological types of the body of F.hepatica, F.gigantica and the resemblance between F.hepatica and F.gigantica. Specified Polymerase Chain Reaction (PCR) showed that they are all F.gigantica, mean that F.gigantica has high potential of morphological disguise. That all of the Fasciola detected on the cattle from Binhdinh and Khanhhoa are F.gigantica, that existence of F.hepatica population in this region maybe very low. Furthermore, a variant of Redia from F.gigantica with more Cercaria than other common types.