Morphological and molecular characterization of Paragonimus westermani in northeastern India.

Evidence for the presence of lung flukes of the Paragonimus westermani in India remains scant. In particular, evidence based on morphology of adult worms is lacking. Metacercariae of the genus Paragonimus, recovered from crabs in two regions of northeastern India, were raised to adulthood in laboratory rats. Morphologically, these worms appear to be P. westermani. DNA sequences from the second internal transcribed spacer (ITS2) and a portion of the ribosomal large subunit gene (28S) of the nuclear ribosomal RNA gene repeat, as well as fragments of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1) genes, all supported this identification. Molecular phylogenetic methods were used for studying the relatedness of these Indian flukes with counterparts from southeast and far-east Asia. Molecular data showed that Indian representatives of the P. westermani complex represent a distinct lineage. It is unclear whether the Indian form can cause disease in humans as some members of the complex do elsewhere.