Transmission dynamics and epidemiology of BSE in British cattle

Anderson, Roy M.; Donnelly, Christl A.; Ferguson, Neil; Woolhouse, Mark; Watt, Christopher J.; Udy, H. J.; MaWhinney, Samantha; Dunstan, S. P.; Southwood, T. R. E.; Wilesmith, J. W.; Ryan, J. B. M.; Hoinville, Linda; Hillerton, J.E.; Austin, A. R.; Wells, G. A. H.

doi:10.1038/382779a0

Cited by 544 publications

(414 citation statements)

References 28 publications

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“…Because of the long incubation period of BSE, which is around five years [3,6,14], the inquiries took place up to ten years after the birth of the case or control. This explains why some farms (2 cases and 13 controls contacted for the study) did not preserve invoices or identification documents referring to bovines, sometimes already dead.…”

Section: Discussionmentioning

confidence: 99%

“…Data were collected on the size of these operations and the farming practices such as purchase of feedstuffs and batch rearing (for operations concerned by that practice). The results presented here concern the first two years of life of cases and controls, this period being regarded as the more at risk for infection [3,6,18]. Data were encoded and stored in an Access database (Microsoft Access 2000, Microsoft Corporation, Redmond, WA, USA).…”

Section: Data Collectionmentioning

confidence: 99%

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Case-control study on feed risk factors for BSE cases born after the feed ban in France

Jarrige¹,

Ducrot²,

Cazeau³

et al. 2007

Vet. Res.

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-In France, after the ban on meat and bone meal (MBM) in cattle feeding in June 1990, cases of Bovine Spongiform Encephalopathy (BSE) have continued to be detected in bovines born after that ban (called BAB cases). A case-control study was therefore carried out to determine the way these cases were contaminated. A multivariate conditional model was built adjusting for the production type of the animals and taking into account the herd size. The results confirmed that feeding cattle with proprietary concentrates was at risk for BSE, with an adjusted odds ratio of 6.8 (2.5; 18.7) for the consumption of less or three different proprietary concentrates and 17.6 (5.7; 54.8) for more than three, when comparing with no consumption of proprietary concentrates, considering feeding of bovines before the age of two. The results suggest that cross-contaminations by MBM in bovine concentrates have occurred after 1990. To a lesser extent, on-farm cross-contaminations, i.e. consumption by cattle of feedstuffs initially dedicated to other animals and which could legally contain MBM, have probably also existed, since the presence on farms of poultry fed purchased feed involved an increased risk of BSE with an odds ratio of 1.8 (1.1; 3.0). The use of milk replacers, which often incorporates animal fats, was also at risk with an odds ratio of 1.8 (1.0; 3.1).BSE / cross-contamination / cattle feeding / proprietary concentrates / France

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Section: Discussionmentioning

confidence: 99%

Section: Data Collectionmentioning

confidence: 99%

Case-control study on feed risk factors for BSE cases born after the feed ban in France

Jarrige¹,

Ducrot²,

Cazeau³

et al. 2007

Vet. Res.

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“…From 2001 to 2005, a total of around 50 million cattle have been tested in the framework of the surveillance program in the EU, of which around 7 000 cases proved BSEpositive (Tab. I) 1,3,4,5,6 . The youngest case of BSE to date was found by passive surveillance in the UK 7 and was 20 months old.…”

Section: Active Surveillancementioning

confidence: 99%

“…They had a great effect in decreasing the epidemic, which was strongly observed in the UK [38], but were not fully effective in controlling the disease, so that further measures were taken. In the nineties, modelling studies were carried out on the British data [4] that estimated retrospectively the size of the epidemic and the key parameters of it, such as the age at infection and the incubation time. In the ten years since the initial modelling, new diagnostic tools have been developed and widely used in the EU; through a comprehensive active surveillance, the disease has been discovered in many countries, and a large amount of work has been done by different teams in the field of epidemiology and modelling.…”

Section: Introductionmentioning

confidence: 99%

Review on the epidemiology and dynamics of BSE epidemics

Ducrot¹,

et al. 2008

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-The paper describes how the comprehensive surveillance of bovine spongiform encephalopathy (BSE) and studies carried out on these data has enhanced our knowledge of the epidemiology of BSE. Around 7 000 BSE cases were detected through the screening of about 50 million cattle with rapid tests in Europe. It confirmed that the clinical surveillance had a poor capacity to detect cases, and also showed the discrepancy of this passive surveillance efficiency between regions and production types (dairy/beef). Other risk factors for BSE were being in a dairy herd (three times more than beef), having a young age at first calving (for dairy cattle), being autumn-born (dairy and beef), and being in a herd with a very high milk yield. These findings focus the risk on the feeding regimen of calves/heifers. Several epidemiological studies across countries suggest that the feedborne source related to meat and bone meal (MBM) is the only substantiated route of infection -even after the feed ban -, while it is not possible to exclude maternal transmission or milk replacers as a source of some infections. In most European countries, the average age of the cases is increasing over time and the prevalence decreasing, which reflects the effectiveness of control measures. Consistent results on the trend of the epidemic were obtained using back-calculation modelling, the R 0 approach and Age-Period-Cohort models. Furthermore, active surveillance also resulted in the finding of atypical cases. These are distinct from previously found BSE and classified in two different forms based on biochemical characteristics; their prevalence is very low (36 cases up to 1st September 2007), affected animals were old and some of them displayed clinical signs. The origin and possibility of natural transmission is unknown.

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“…This data included the date of birth, date of death, date of BSE diagnosis and the exact geographic coordinates of the farms where the cases spent most of their first year after birth. It was assumed that the cases were exposed with the BSE agent on these locations [2]. One hundred and eleven cases were found as clinical suspects, 84 in the active surveillance system and 21 in the voluntary testing.…”

Section: Data Sourcesmentioning

confidence: 99%

BSE, feed and cattle in Switzerland: Is there a spatial relation?

et al. 2007

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-Cross-contamination of cattle feed with meat and bone meal (MBM) allowed in feed for other species is regarded as the current hypothesis for the infection pathway of Bovine Spongiform Encephalopathy (BSE) cases occurring after the implementation of a ban on feeding MBM to cattle. This study was aimed at establishing a spatial relation between BSE cases in Switzerland and the findings of MBM in cattle feed. A cluster analysis and a cohort study were performed. Two hundred sixteen BSE cases born after December 1990 and detected until August 1st 2005, screening data of 504 feed producers between 1996 and 2001 and population data from the Swiss 2001 cattle census were included. The cluster analysis showed feed producer, positive for MBM contaminations in cattle feed, as possible cluster centres for BSE cases. In the cohort study, farms within a radius of 2 and 10 km around positive feed producers showed significantly higher odds to have a BSE case than the control group. The odds ratio and its 95% confidence interval were 2.23 (1.26-3.93) for the 2 km radius and 1.38 (1-1.9) for the 10 km radius. The results provide evidence for a spatial relation between cross-contamination and BSE occurrence. These findings support the hypothesis of cross-contamination to be an important route for BSE transmission after a feed ban. bovine spongiform encephalopathy / compound feed / cluster / spatial analysis / feed producer

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Transmission dynamics and epidemiology of BSE in British cattle

Abstract: A comprehensive analysis of the bovine spongiform encephalopathy (BSE) epidemic in cattle in Great Britain assesses past, present and future patterns in the incidence of infection and disease, and allows a critical appraisal of different culling policies for eradication of the disease.

Cited by 544 publications

References 28 publications

Case-control study on feed risk factors for BSE cases born after the feed ban in France

Case-control study on feed risk factors for BSE cases born after the feed ban in France

Review on the epidemiology and dynamics of BSE epidemics

BSE, feed and cattle in Switzerland: Is there a spatial relation?

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