Gross, histopathology and molecular diagnosis of oesophagostomosis in sheep.

A total of 120 tissue samples (Rumen, reticulum, omasum, abomasum, small intestine and large intestine) were collected from slaughter houses in Chennai, Kanchipuram and Tiruvallur districts and five samples from necropsy room at Department of Veterinary Pathology, Madras Veterinary College, Chennai, Tamil Nadu. Overall prevalence of GI parasites was 52.00%. Among the positive samples, single infection was found to be more (53.84%) than themixed infection (46.15%). Out of which, oesophagostomosis was 17.00% and found as single infection. In oesophagostomosis, significant gross lesions observed in the small and large intestine were multiple small to large, round to irregular, hard, fibrotic, raised nodules. The wall of the large intestine was greatly thickened and oedematous and the nodules were seen projecting into the lumen and mucosal surface was intact. On histopathological examination, ileum of sheep showed parasitic nodules with central baso-eosinophilic necrotic area, larval stages in the necrotic area, surrounded by layers of inflammatory cells and finally encapsulated in a thick fibrous connective tissue capsule. Immunohistochemistry (IHC) with Vimentin showed intense cytoplasmic positive signals DAB Brown. PCR was carried out targeting ITS2 regions of the O. columbianum and O. venulosum. DNA isolated from both the faecal eggs and adult worms showed good amplification.