Molecular detection and phylogenetic analysis of Schistosoma indicum in slaughtered cattle from Chennai city, India

Bovine visceral schistosomosis is a neglected tropical blood fluke disease causing economic losses in cattle industry. One hundred and eighty mesentery samples of cattle were collected from Perambur slaughter house, Chennai, Tamil Nadu, during a period of October 2019 - March 2020 for screening visceral schistosomosis. Schistosoma indicum was identified in eleven mesenteries based on gross and microscopic characters and worm number varied from 1-114 per mesentery. Morphological identification was further confirmed by PCR targeting the 16S rRNA gene (606 bp). The amplified product was also subjected to sequencing and phylogenetic analysis, which revealed three different clades with the present isolate belonging to clade II. The percentages of nucleic acid identity for the sequence of Indian S. indicum isolate obtained in this study revealed 100 % identity to S. indicum of Bangladesh. The present study revealed the occurrence of S.indicum in cattle and phylogenetic analysis of gene sequence was also carried out from Tamil Nadu for the first time. Broader studies are needed to understand the epizootiology of this important disease affecting cattle in India.