Morphomolecular characterization of Strongylus vulgaris isolated from donkeys with special references to histopathological study on the affected organs.

Equine gastrointestinal tract is infected with Strongylus vulgaris (S. vulgaris) which is highly pathogenic parasite for its harmful effect on cranial mesenteric artery during its migration. So, this study was applied for identification of S. vulgaris in donkeys ultramorphologically and molecularly. In addition to, detection of the pathological effect of larval stage of S. vulgaris on the mesenteric arterial system using histopathology and immunohistochemistry. During the period from September to December; 2019, 60 male and 20 female donkeys at the Giza Zoo was postmortem examined. S. vulgaris adults and larvae were collected from the large intestine and cranial mesenteric arteries (CMAs), respectively. Ultramorphological examination of the collected adults was done using scanning electron microscope (SEM). DNA was extracted from 5 larvae and 6 adults for further conventional PCR studies and sequencing of the internal transcriped spacer 2 (ITS2) gene. The ITS2 gene were amplified and showed bands at 148 base pair (bp). The ITS2 gene nucleotide sequences of all isolates were aligned using Basic Local Alignment Search Tool (BLAST). Histological sections of S. vulgaris affected mesenteric arteries exhibited the presence of the parasite larvae either in the lumen with thrombus formation or attached to the intima. Most of the detected inflammatory cell populations were CD68-positive cells. From these results, it can be concluded that the ribosomal spacers genes could be used as markers for Strongylus species identification in eggs collected from equine feces as a beneficial method of diagnosis. Also, it could be important in disease surveillance, improving preventive measures and developing an effective control strategy. © Indian Society for Parasitology 2022.