SACM - Ireland
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9656
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Item Restricted Johne’s disease in farmed sika deer (Cervus nippon) in Ireland(Saudi Digital Library, 2026) Alotaibi, Nasser Mathkar; Hanne, JahnsAlthough Johne’s disease (JD), caused by Mycobacterium avium subspecies paratuberculosis (MAP), has been described in several deer species, this thesis provides the first comprehensive characterisation of MAP infection in farmed sika (Cervus nippon) worldwide. The aim of this study was to characterise MAP infection in farmed sika deer at different stages of infection using histopathology, liquid culture and whole genome sequencing (WGS). Rapid commercially available diagnostic tests such as IS900 qPCR, and ELISA assays were evaluated for their use in diagnosing JD in this species for the first time. Tissue, faecal and / or serum samples were collected from 119 farmed sika deer at various stages of disease in an MAP affected herd. The VetMAX MAP 2.0 IS900 qPCR assay, correlated well with results from liquid culture and is an effective method for detecting MAP faecal shedding in sika deer. Whole genome sequencing of four isolates collected from different years, and disease stages showed that all belonged to the Cattle-type strain and were genetically identical, suggesting the presence of a highly clonal strain within the herd. One third of subclinically infected sika deer had no microscopic lesions in the ileocaecal lymph node or ileum, while the remainder showed mild to moderate focal granulomatous lesions with few or no detectable acid-fast bacilli. In contrast, the clinical cases were dominated by diffuse granulomatous lesions, high lesion severity scores, and abundant acid-fast bacilli in both tissues. Of the two commercial ELISA assays (ID.VET and IDEXX), and the Paralisa™, all three assays showed excellent specificity (100%), but Paralisa™ (48%) and ID.VET (43%) were considerably more sensitive than IDEXX (4%). An eight year-monitoring study of a small sika deer herd found no detectable spread of infection from an intermittently moderately-shedding stag. Overall, this thesis provides important insight into the progression, diagnostics, and transmission of JD in sika deer, that with inform the future detection, monitoring and management of this disease in this species.9 0