RESUMEN
Freshwater crabs (Potamiscus manipuriensis), commonly consumed as local delicacies by the native people in the state of Manipur, were found to harbour metacercariae of Microphallus sp. (Family Microphyllidae), which were morphologically different from metacercariae of Microphallus spp reported earlier from different regions. So, PCR-based molecular characterization of this metacercaria was done utilizing rDNA marker regions: larger subunit (LSU) or 28S (D1-D3 region) and inter-transcribed spacer 2 (ITS2). Sequence and phylogenetic analyses confirmed that the taxon under study belonged to family Microphyllidae of genus Microphallus.
RESUMEN
Food-borne trematode infections, which are mainly transmitted through consumption of inadequately cooked or raw fish and crabs, affect a large section of population, particularly in Southeast Asian countries, thus eliciting a remarkable morbidity and causing serious damage to health. In India, centering in several mountainous regions of the Northeast, the natives have the habit of consuming such fish or crabs that still sustain viable infective larval stage (metacercaria) of trematode flukes in their muscle tissue. The present study was undertaken to ascertain the spectrum of metacercarial diversity in commonly edible freshwater fishes and crab species in the northeastern state of Manipur and to adjudge their zoonotic potential, if any. Commonly edible fishes belonging to 15 species from 12 localities and crabs belonging to 2 species from 11 localities across Manipur state were surveyed for the purpose. The study revealed that 3 species of fishes (Channa punctatus, C. straitus and Wallago attu) harboured 4 different types of metacercariae belonging to 4 trematode families-Euclinostomum heterostomum (Clinostomidae); Lophosicyadiplostomum sp. and Posthodiplostomum sp. (Diplostomidae); and Polylekithum sp. (Allocreadiidae) in addition to adult flukes of Isoparorchis hypselobagri (Isoparorchiidae). Among these, metacercariae of Posthodiplostomum showed the highest prevalence (2.33 %) though a low abundance, while for other species the prevalence ranged between 0.25 and 1.19 %. The crab species (Barythelphusa lugubris masoniana and Potamiscus manipuriensis) were found infected with 4 different types of metacercariae representing the genera Paragonimus (Troglotrematidae) and Microphallus (Microphallidae). The paragonimids showed a higher rate of occurrence (~4-25 %) compared to microphallids (~15 %). The crustaceans surveyed emerged as prospective intermediate hosts for lungflukes. Identifying the potent vectors for zoonotic parasites helps in control measures towards their transmission to higher mammals.