Evaluation of paragonimus metacercariae isolated from Maydelliathelphusa Lugubris and morphological characterization of Paragonimus Westermani recovered from an experimental model

Background: Humans acquire Paragonimus westermani (lung flukes) infestation by consumption of crabs and crayfish harboring Paragonimus metacercariae. This study was designed to evaluate the prevalence of P. westermani infection in fresh water crabs found in Manipur, India. The morphological characterization of adult fluke recovered from Wister rats infected with P. metacercariae was also studied. Materials and Methods: The freshwater crabs were collected from the mountain streams of Churachanpur district, Manipur, India. P. metacercariae were harvested from the crab extract under a stereomicroscope. To recover adult flukes, twenty P. westermani-type metacercariae were injected intraperitoneally to Wister rats. The adult fluke recovered from Wister rats were stained with borax carmine, and the whole mount was used for morphological assessment. Results: Crabs of species, Maydelliathelphusa lugubris, were found to harbor Paragonimus heterotremus- and westermani-type metacercariae. Two migratory flukes were recovered from the lung surface of the Wister rats injected intraperitoneally with metacercariae. The morphological features of the mounted specimen of adult fluke recovered showed six lobed ovaries with terminal branching and five lobed testes. On the basis of the morphological features, the species was identified as P. westermani despite the atypical features of its metacercariae. Conclusion: Here, we report the role of M. lugubris fresh water crab species as natural permissive hosts of lung fluke (P. westermani) in Manipur region of India.