Incidence and pathological effects during encysted progenetic Euclinostomum heterostomum metacercariae infection in the freshwater fish spotted snakehead (Channa punctatus)
Authors:   Department of Zoology, Vinoba Bhave University, Hazaribagh-825 301, India, Devnath S. , Kumar V. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Roy S. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Jana A.K. ,   Department of Zoology, Vinoba Bhave University, Hazaribagh-825 301, India, Dhar S. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Bisai K. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Parida S.N. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Verma A. ,   Department of Zoology, Vinoba Bhave University, Hazaribagh-825 301, India, Das B.K. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India, Behera B.K. ,   Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Barrackpore-700 120, India
Published: June 2024

Aim: To assess the incidence and pathological effects during encysted progenetic Euclinostomum heterostomum metacercariae infestation in the freshwater fish spotted snakehead (Channa punctatus). Methodology: Samples of Channa punctatus were collected from Tilaiya Reservoir, Koderma, Jharkhand, India, during pre-monsoon, monsoon, and post-monsoon seasons. The encysted metacercariae trematodes were isolated from Channa punctatus. Characterization was performed based on the morphology and sequencing analysis of a partial 18S rRNA gene. Further, the kidney and liver samples from infected fish were subjected to histopathological studies. Prevalence, abundance, and Intensity of infection were further determined. Results: Morphological identification suggests that the encysted metacercariae belonged to Digenean trematodes of genera Euclinostomum, and amplification of partial sequence of 18S rRNA, and phylogenetic analysis revealed the isolated metacercariae were Euclinostomum heterostomum. The histopathological study of the kidney showed hepatocyte degeneration, cytoplasmic vacuolation, and nuclear transformations. Liver fibrosis was observed in Channa punctatus. The prevalence during pre-monsoon, monsoon, and post-monsoon season ranged from 66.1% to 81.1%, abundance from 0.74 to 0.92, and intensity ranged from 1 to 1.14 using the Margolis formula. Interpretation: The study highlights the infestation of Euclinostomum heterostomum in Channa punctatus during the pre- monsoon climate appears favorable for the abundance of parasites. Hence, a proper inspection before consumption is necessary. Key words: Euclinostomum heterostomum, Infestation, Metacercariae, Parasites, Progenetic infection