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Dichelobacter nodosus and footrot in Swedish sheep

increased knowledge and improved laboratory diagnostics

Frosth, Sara (2016). Dichelobacter nodosus and footrot in Swedish sheep. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2016:112
ISBN 978-91-576-8727-2
eISBN 978-91-576-8728-9
[Doctoral thesis]

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Abstract

Ovine footrot is a contagious bacterial disease primarily caused by Dichelobacter nodosus. Footrot affects the feet of sheep and is characterised by two major clinical presentations. The milder form consists of inflammation confined to the interdigital space (interdigital dermatitis or benign footrot) and the more severe form includes underrunning of the hoof horn (underrunning or virulent footrot). Disease severity is dependent on several factors including the virulence of the D. nodosus strain, environmental conditions, farming practices, host susceptibility, and co-infecting bacteria.

In Sweden, ovine footrot was first diagnosed in 2004, but fast and sensitive diagnostics for D. nodosus were not available. Likewise, knowledge was missing about the D. nodosus strains and co-infection with other lameness-associated bacteria. Hence the overall aim of this thesis project was to increase the knowledge about ovine footrot in Swedish sheep and to improve laboratory diagnostics for it.

In this thesis project, sensitive and specific real-time PCR methods to detect and discriminate between virulent and benign strains of D. nodosus were developed and used to characterise D. nodosus from Swedish sheep. The results showed that most of the Swedish D. nodosus are benign and that the virulent type is uncommon. D. nodosus isolates from seven other countries included in the study showed that the D. nodosus genome is highly conserved and that it exists as a globally distributed bimodal population. Furthermore, D. nodosus is mainly associated with the early stages of footrot whereas Fusobacterium necrophorum is associated with the later ones. This confirms the suggested role of F. necrophorum as an opportunistic pathogen rather than the primary pathogen. Although previously proposed, there was no evidence of Treponema spp. in disease development. Finally, a sample pooling method was developed to meet the demands for cost-efficiency in control programs. The method allows samples to be analysed in groups of five with no loss of sensitivity compared to individual samples. It has been implemented in the Swedish Footrot Control Program as a result of this thesis project.

Authors/Creators:Frosth, Sara
Title:Dichelobacter nodosus and footrot in Swedish sheep
Subtitle:increased knowledge and improved laboratory diagnostics
Series/Journal:Acta Universitatis agriculturae Sueciae (1652-6880)
Year of publishing :2016
Depositing date:11 November 2016
Volume:2016:112
Number of Pages:71
Papers/manuscripts:
NumberReferences
IFrosth, S., Slettemeås, J.S., Jørgensen, H.J., Angen, Ø., and Aspán, A (2012). Development and comparison of a real-time PCR assay for detection of Dichelobacter nodosus with culturing and conventional PCR: harmonisation between three laboratories. Acta Vet. Scand. 54(6).
IIKennan, R.M., Gilhuus, M., Frosth, S., Seemann, T., Dhungyel, O.P.,Whittington, R.J., Boyce, J.D., Powell, D.R., Aspán, A., Jørgensen, H.J.,Bulach, D.M., and Rood, J.I (2014). Genomic evidence for a globally distributed, bimodal population in the ovine footrot pathogen Dichelobacter nodosus. mBio 5(5):e01821-14.
IIIFrosth, S., König, U., Nyman, A.K., Pringle, M., and Aspán, A (2015). Characterisation of Dichelobacter nodosus and detection of Fusobacterium necrophorum and Treponema spp. in sheep with different Clinical manifestations of footrot. Vet. Microbiol. 179(1-2), 82-90.
IVMaboni, G., Frosth, S., Aspán, A., and Tötemeyer, S (2016). Ovine footrot: new insights into bacterial colonisation. Vet. Rec. 179(9).
VFrosth, S., König, U., Nyman, A.K., and Aspán, A (2016). Sample pooling for real-time PCR detection and virulence determination of the footrot pathogen Dichelobacter nodosus. In manuscript
Place of Publication:Uppsala
Publisher:Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-8727-2
ISBN for electronic version:978-91-576-8728-9
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:L Animal production > L73 Animal diseases
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Microbiology (Microbiology in the medical area to be 30109)
(A) Swedish standard research categories 2011 > 3 Medical and Health Sciences > 301 Basic Medicine > Cell and Molecular Biology
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 403 Veterinary Science > Pathobiology
Agrovoc terms:sheep, foot rot, dichelobacter nodosus, fusobacterium necrophorum, treponema, virulence, immunodiagnosis, genomes, genetic variation, pcr, sweden
Keywords:Dichelobacter nodosus, Ovine footrot, diagnostics, virulence, serogroup, genome, real-time PCR, pooling of samples, Fusobacterium necrophorum, Treponema spp.
URN:NBN:urn:nbn:se:slu:epsilon-e-3783
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3783
ID Code:13845
Faculty:VH - Faculty of Veterinary Medicine and Animal Science
Department:(VH) > Dept. of Biomedical Sciences and Veterinary Public Health
External funders:Knut and Alice Wallenberg Foundation and Stiftelsen Lantbruksforskning and Statens veterinärmedicinska anstalts forskningsfond
Deposited By: Sara Frosth
Deposited On:14 Nov 2016 08:35
Metadata Last Modified:26 Jul 2017 15:37

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