Infectivity in the ileum of cattle challenged orally with bovine spongiform encephalopathy

Wells, G. A. H.; Dawson, M.; Hawkins, S. A. C.; Green, R. B.; Dexter, Ian; Francis, M. E.; Simmons, Marion; Austin, A. R.; Horigan, M.

doi:10.1136/vr.135.2.40

Cited by 132 publications

(90 citation statements)

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“…In cattle experimentally infected with a high oral dose of BSE, infectivity was present in the ileum six months after oral infection [71,73] and in the tonsil ten months after oral infection (the latter only detectable using the more sensitive bovine transgenic mouse and cattle bioassay) [16,74]. In these animals PrP Sc was immunohistochemically detected in TBM of the ileal Peyer's patches but not in the tonsil [26,63,74].…”

Section: In Naturally Infected Bse Cases No Prpmentioning

confidence: 94%

TSE pathogenesis in cattle and sheep

2008

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-Many studies have been undertaken in rodents to study the pathogenesis of transmissible spongiform encephalopathies (TSE). Only a few studies have focused on the pathogenesis of bovine spongiform encephalopathy (BSE) and scrapie in their natural hosts. In this review, we summarize the most recent insights into the pathogenesis of BSE and scrapie starting from the initial uptake of TSE agents and crossing of the gut epithelium. Following replication in the gut-associated lymphoid tissues (GALT), TSE agents spread to the enteric nervous system (ENS) of the gut. Infection is then carried through the efferent fibers of the post-ganglionic neurons of the parasympathetic and sympathetic nervous system to the pre-ganglionic neurons in the medulla oblongata of the brain and the thoracic segments of the spinal cord. The differences between the pathogenesis of BSE in cattle and scrapie in sheep are discussed as well as the possible existence of additional pathogenetic routes.

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Section: In Naturally Infected Bse Cases No Prpmentioning

confidence: 94%

TSE pathogenesis in cattle and sheep

2008

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“…Up to the early 2000s, most of the bioassays for the detection/measurements of BSE infectivity relied on mouse inoculation bioassay with conventional RIII mice (Fraser and Foster, 1993;Wells et al, 1994a;Bradley, 1996).…”

Section: Riii Mice Modelmentioning

confidence: 99%

Scientific Opinion on BSE risk in bovine intestines and mesentery

Publication¹

2014

EFS2

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Bovine intestines and mesenteries in the European Union (EU) have to be removed from the food and feed chain. The opinion provides a quantitative assessment of the Bovine Spongiform Encephalopathy (BSE) infectious load that might enter the food and feed chain yearly if bovine intestine and mesentery from animals born and raised in the EU would be re-allowed for consumption. Data on the evolution of the BSE infectious titre; and of the weight of histological structures accumulating BSE infectivity, were collected. The Cattle TSE Monitoring Model (C-TSEMM) was used to estimate the number of BSE infected cattle entering undetected in the food and feed chain yearly. A model named TSEi was developed to estimates the BSE infectious load in tissues from infected animals at different ages and the total yearly infectious load that could enter the food and feed chain in the EU27. In BSE infected cattle, the infectivity associated with intestine and mesentery reaches its maximum in animals younger than 18 months and then progressively declines to a minimum value in animals older than 60 months. Due to the decline of the BSE prevalence in the EU, between 2007 and 2012, the yearly amount of BSE infectivity associated with intestine and mesentery (sent to destruction) from animals entering the food and feed chain was reduced by a factor of 10. However, over this period, the maximum level of exposure to the BSE agent for individuals that would have consumed these tissues remained stable. Finally, the TSEi model indicated that the removal of the last four metres of the small intestine and of the caecum from the food and feed chain would result in a major reduction of the BSE exposure risk associated with intestine and mesentery in cattle. (2011) and Kaatz et al. (2012). James Hope and Marion Simmons are acknowledged for kindly disclosing to EFSA raw data on BSE infectivity in bovine intestine; and the titration in RIII mice of the BBP12/92 inoculum used in the Buschmann and Groschup (2005) paper. * Three minor editoral changes were made: The number of atypical cases in 2005 in Table 11 © European SUMMARYFollowing a request from the European Commission (EC), the Panel on Biological Hazards (BIOHAZ) was asked to deliver a scientific opinion on the BSE risk in Bovine intestine and mesentery.Currently bovine intestines and mesenteries in the European Union (EU) are classified as Specified Risk Material (SRM) according to Regulation (EC) 999/2001 4 (Reg. 999/2001) as amended -the TSE Regulation -and have to be removed from the food and feed chain. SRM are considered as the animal tissues potentially containing the highest level of Transmissible Spongiform Encephalopathies (TSEs) infectivity. Thus, the removal of SRM is the most important public health protection measure against TSEs in the EU.In this context, the BIOHAZ Panel was requested to assess quantitatively the Bovine Spongiform Encephalopathy (BSE) infectious load that might enter the food and feed chain yearly if bovine intestines (fresh or after processing into c...

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“…meal (MBM) contaminated by a scrapie-like agent derived from sheep or cattle. The oral route of infection for transmissible spongiform encephalopathy (TSE) agents has been demonstrated experimentally (Barlow & Middleton 1990;Fraser et al 1992;Middleton & Barlow 1993;Wells et al 1994;MAFF 1996). Subsequent epidemiological investigations undertaken in 1988 and 1989 revealed that the consumption of MBM from infected cattle was the probable cause of the rapid development of the epidemic in the cattle population within Great Britain (GB) (Wilesmith et al 1988(Wilesmith et al , 1991.…”

Section: Introductionmentioning

confidence: 99%

The epidemiology of BSE in cattle herds in Great Britain. I. Epidemiological processes, demography of cattle and approaches to control by culling

Donnelly

Ferguson

Ghani

et al. 1997

Phil. Trans. R. Soc. Lond. B

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This paper explores the key epidemiological processes and demographic factors that determined the pattern of transmission of the aetiological agent of bovine spongiform encephalopathy (BSE) in cattle herds in Great Britain (GB). The analyses presented utilize data from published and unpublished experimental studies and from the GB central database of confirmed BSE cases. We review the experimental and epidemiological evidence that has both confirmed indirect horizontal transmission via the consumption of infectious material as the major transmission route and provided information on the duration and variability of the dose–dependent incubation period of BSE in cattle. The epidemiological and genetic data pertaining to the possible existence of maternal transmission and/or genetically variable susceptibility to infection is discussed. The demography of British cattle is characterized and the impacts of key demographic features on the observed epidemic profile are discussed. In the main BSE case database, analyses reveal that BSE cases cluster significantly at both the holding and county scale. Furthermore, analysis of longitudinal patterns reveal substantial temporal within–holding correlation. Such clustering of cases suggests a highly heterogeneous infection process. The paper ends with a discussion of how analyses of spatio–temporal clustering inform the design of targeted culling programmes aimed at reducing future disease incidence. We show how the retrospective implementation of culling policies on the BSE case database allows the qualitative evaluation of policy performance, but that model predictions of future trends in case incidence are required to estimate the precise impact of any current or future programme.

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Infectivity in the ileum of cattle challenged orally with bovine spongiform encephalopathy

Cited by 132 publications

References 0 publications

TSE pathogenesis in cattle and sheep

TSE pathogenesis in cattle and sheep

Scientific Opinion on BSE risk in bovine intestines and mesentery

The epidemiology of BSE in cattle herds in Great Britain. I. Epidemiological processes, demography of cattle and approaches to control by culling

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