Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.

Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, c...

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Autores principales:	David M Wright, Adrian R Allen, Thomas R Mallon, Stanley W J McDowell, Stephen C Bishop, Elizabeth J Glass, Mairead L Bermingham, John A Woolliams, Robin A Skuce
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/911e177e6e23457bac7de026ef49e0f7
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spelling	oai:doaj.org-article:911e177e6e23457bac7de026ef49e0f72021-11-18T08:54:04ZField-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.1932-620310.1371/journal.pone.0074503https://doaj.org/article/911e177e6e23457bac7de026ef49e0f72013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24086351/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, combining data from a nine-year survey of the genetic structure of the M. bovis population in Northern Ireland with detailed records of the cattle population during the same period. We used the size of herd breakdowns as a proxy measure of transmissibility and the proportion of skin test positive animals (reactors) that were visibly lesioned as a measure of virulence. Average breakdown size increased with herd size and varied depending on the manner of detection (routine herd testing or tracing of infectious contacts) but we found no significant variation among M. bovis genotypes in breakdown size once these factors had been accounted for. However breakdowns due to some genotypes had a greater proportion of lesioned reactors than others, indicating that there may be variation in virulence among genotypes. These findings indicate that the current bTB control programme may be detecting infected herds sufficiently quickly so that differences in virulence are not manifested in terms of outbreak sizes. We also investigated whether pathology of infected cattle varied according to M. bovis genotype, analysing the distribution of lesions recorded at post mortem inspection. We concentrated on the proportion of cases lesioned in the lower respiratory tract, which can indicate the relative importance of the respiratory and alimentary routes of infection. The distribution of lesions varied among genotypes and with cattle age and there were also subtle differences among breeds. Age and breed differences may be related to differences in susceptibility and husbandry, but reasons for variation in lesion distribution among genotypes require further investigation.David M WrightAdrian R AllenThomas R MallonStanley W J McDowellStephen C BishopElizabeth J GlassMairead L BerminghamJohn A WoolliamsRobin A SkucePublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 8, Iss 9, p e74503 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q David M Wright Adrian R Allen Thomas R Mallon Stanley W J McDowell Stephen C Bishop Elizabeth J Glass Mairead L Bermingham John A Woolliams Robin A Skuce Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
description	Strains of many infectious agents differ in fundamental epidemiological parameters including transmissibility, virulence and pathology. We investigated whether genotypes of Mycobacterium bovis (the causative agent of bovine tuberculosis, bTB) differ significantly in transmissibility and virulence, combining data from a nine-year survey of the genetic structure of the M. bovis population in Northern Ireland with detailed records of the cattle population during the same period. We used the size of herd breakdowns as a proxy measure of transmissibility and the proportion of skin test positive animals (reactors) that were visibly lesioned as a measure of virulence. Average breakdown size increased with herd size and varied depending on the manner of detection (routine herd testing or tracing of infectious contacts) but we found no significant variation among M. bovis genotypes in breakdown size once these factors had been accounted for. However breakdowns due to some genotypes had a greater proportion of lesioned reactors than others, indicating that there may be variation in virulence among genotypes. These findings indicate that the current bTB control programme may be detecting infected herds sufficiently quickly so that differences in virulence are not manifested in terms of outbreak sizes. We also investigated whether pathology of infected cattle varied according to M. bovis genotype, analysing the distribution of lesions recorded at post mortem inspection. We concentrated on the proportion of cases lesioned in the lower respiratory tract, which can indicate the relative importance of the respiratory and alimentary routes of infection. The distribution of lesions varied among genotypes and with cattle age and there were also subtle differences among breeds. Age and breed differences may be related to differences in susceptibility and husbandry, but reasons for variation in lesion distribution among genotypes require further investigation.
format	article
author	David M Wright Adrian R Allen Thomas R Mallon Stanley W J McDowell Stephen C Bishop Elizabeth J Glass Mairead L Bermingham John A Woolliams Robin A Skuce
author_facet	David M Wright Adrian R Allen Thomas R Mallon Stanley W J McDowell Stephen C Bishop Elizabeth J Glass Mairead L Bermingham John A Woolliams Robin A Skuce
author_sort	David M Wright
title	Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
title_short	Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
title_full	Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
title_fullStr	Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
title_full_unstemmed	Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
title_sort	field-isolated genotypes of mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/911e177e6e23457bac7de026ef49e0f7
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Field-isolated genotypes of Mycobacterium bovis vary in virulence and influence case pathology but do not affect outbreak size.

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