Ovine footrot is an infectious cause of lameness in sheep that has significant economic impact for the UK sheep farming industry. It is also a major concern for animal health and welfare. The causal agent is Dichelobacter nodosus, and Fusobacterium necrophorum is an opportunistic secondary pathogen that increases disease severity. The primary reservoirs for F. necrophorum in sheep were believed to be sheep faeces and the environment, however, no studies had demonstrated the presence of F. necrophorum at either of these sites. Two longitudinal studies (Study A and Study B) were conducted to determine reservoir sites of F. necrophorum in ovine footrot. Study A included 10 sheep sampled on four occasions at two week intervals. Study B included 40 sheep sampled weekly for 20 weeks. Samples collected from sheep and their environment were foot swabs, mouth swabs, faeces, soil and grass. Quantitative PCR was used to detect and quantify F. necrophorum. A multiple locus variable number tandem repeat analysis (MLVA) community typing scheme for F. necrophorum was developed and validated, and used to analyse samples from Study A and Study B. Contrary to prior assumption, the environment was not a significant reservoir of F. necrophorum. F. necrophorum persisted in sheep, primarily on feet with footrot. MLVA indicated that the strains of F. necrophorum found on the feet of sheep were closely related, and they may therefore share characteristics that make them well adapted to feet and footrot. Mouths and faeces were an intermittent reservoir for the strains of F. necrophorum involved in footrot. Mouths and faeces may therefore facilitate persistence of F. necrophorum in the absence of footrot, or facilitate transmission of F. necrophorum between flocks. Mouths were a persistent reservoir for strains of F. necrophorum not involved in footrot.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:731433 |
| Date | January 2017 |
| Creators | Clifton, Rachel |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/97437/ |
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