UTTAR PRADESH JOURNAL OF ZOOLOGY

The freshwater snail Indoplanorbis exustus (Deshayes, 1834) belonging to the family Planorbidae, acts as the sole intermediate host for several trematodes of medical and economic importance. These include zoonotic schistosomes and echinostomes. However, studies on cercarial identification from aquatic snails in the northeastern region are scarce. This study aims to employ morphological and molecular tools to identify specific Echinostome cercariae in snails. Snails (Indoplanorbis exustus) were collected from different villages of Dimapur district of Nagaland and identified morphologically. Of the 2,000 snails examined, 60 tested positive for Echinostome cercariae, indicating a 3 percent prevalence. Key morphological traits included an elongated oval body with an unforked tail, a mid-ventral circular sucker, and an oral sucker encircled by a subtle spiny collar. Numerous cystogenous glands (giving a dark appearance) were present, eyespots were absent, and the oral sucker lay distinctly apart from the ventral sucker. Cercarial DNA was extracted and amplified using PCR. The resulting DNA products were sequenced, and the ITS2 region was analyzed for phylogenetic identification. Genotypic characterization based on ITS2 demonstrated a 95% homology with Echinostoma trivolvis, 99% with E. malayanum, and 97% with Artyfechinostomum sufratyfex. Furthermore, there was a 97% similarity with E. revoltum, E. trivolvis, and E. caproni. Therefore, supported by the distinctive collar spines and strong ITS2 homology (up to 99 %) with the recognized E. revolutum-group species, the identification was conclusive. The combination of morphological and molecular approaches provides a comprehensive understanding of the prevalence and genetic diversity of Echinostome cercariae in snail populations in Nagaland. This also research contributes to the accurate diagnosis of snail-borne diseases, facilitating effective control measures and minimizing their impact on domestic livestock in India.