Ruminal Lesions in Dairy Cows Naturally Infected by Calicophoron microbothrioides (Trematoda: Paramphistomidae).

Abstract

Calicophoron microbothrioides is a relatively new trematode species reported in domestic ruminants in the Cajamarca Valley (Peru). This species poses a significant endemic risk to domestic ruminants in the local livestock; however, histopathological aspects of the infection remain understudied. This study aims to describe the histological ruminal lesions induced by C. microbothrioides in naturally infected Holstein cows. Ten cows were sampled, collecting 1 cm³ of rumen tissue from affected areas (rough areas without ruminal papillae) in positive cases during post-mortem inspections. Control samples were taken from the rumen tissue of cows not infected with C. microbothrioides. The samples were processed using the paraffin embedding technique and stained with hematoxylin-eosin. The rumen flukes exhibited a pink and shiny color, with a curved conical shape (concave ventral region), and the anterior section slimmer than the posterior one (length 5.45 ± 2.50 mm and width 2.8 ± 0.58 mm). Histology revealed cellular degeneration, inflammation, and tissue necrosis in all affected animals. These findings highlight the impact of C. microbothrioides infection in adult cows, leading to marked histopathological alterations in the rumen wall. Given the importance of these results, there is a need for further studies on this parasite, considering its potential threat to the health and productivity of local ruminants.