Morphological and Molecular Identification of Passalurus Ambiguus Rudolphi, 1819 in Domestic Rabbits (Oryctolagus Cuniculus) in Qena Governorate, Upper Egypt

Abstract Domestic rabbits in Egypt are used commercially for meat, but gastrointestinal disorders can affect production. Passalurus ambiguus is an intestinal parasite that infects the rabbit causing intestinal problems and death in severe cases. The present study collected domestic rabbits from several locations tgroughout the Qena Governorate in Upper Egypt. Passalurus ambiguus worms were detected in 90 out of 200 rabbits (45%). They were described morphologically using light and scanning electron microscopy. Males measured 4.622 mm (2.838–7.172 mm) in length and 0.278 mm (0.139–0.558 mm) in width. Females measured 5.622 mm (2.347–9.532 mm) in length, 0.314 mm, and (0.185–0.381 mm) in width. Phylogenetic results confirmed the identification of the worms as Passalurus ambiguus. They appeared as small white nodules in the appendix of the rabbits examined. Histopathologically, a heavy worm burden was observed inside the appendiceal lumen, among crypts, and inside the lymphoid follicles. The heavy worm infestation leads to hyperplasia in the epithelial lining of the appendix and the follicles resulting in lumen obstruction. Granulomatous reactions were induced due to irritation and injury by the worm. It could be concluded that morphological features, molecular phylogenetic data, and histopathological findings clearly identified the present species as as Passalurus ambiguus Rudolphi, 1819.