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

Jarrige, Nathalie; Ducrot, Christian; Cazeau, Géraldine; Morignat, Eric; Bonnardière, Claude La; Calavas, Didier

doi:10.1051/vetres:2007011

Cited by 14 publications

(10 citation statements)

References 24 publications

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“…Our results agree with those of the case-control study (23), which did not provide evidence that use of mineral and vitamin compounds affect risk for BSE; the authors considered that the implication of animal DCP as a source of BSE, if it existed, should have been marginal. In contrast, a risk analysis by the European Food Safety Agency (www.efsa.…”

Section: Discussionsupporting

confidence: 86%

“…This result favors the effect of cross-contamination of cattle feed with MBM-containing feed for monogastric species as a source of BSE for cattle born after the ban of MBM. A recent epidemiologic study in France (23) clearly showed that cattle that consumed feed from factories were at risk for BSE after the feed ban; it also showed that mixed farms were at a higher risk for BSE, which indicates that cross-contamination has possibly occurred on farms (by feeding monogastric-species feed to bovines). These fi ndings are in agreement with our results; both studies complement each other and raise the question of effectiveness of the ban that was initially restricted to bovines and belatedly extended to other species to reduce cross-contamination.…”

Section: Discussionmentioning

confidence: 99%

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Bovine Spongiform Encephalopathy and Spatial Analysis of the Feed Industry

Paul¹,

Abrial²,

Jarrige

et al. 2007

Emerg. Infect. Dis.

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In France, despite the ban of meat-and-bone meal (MBM) in cattle feed, bovine spongiform encephalopathy (BSE) was detected in hundreds of cattle born after the ban. To study the role of MBM, animal fat, and dicalcium phosphate on the risk for BSE after the feed ban, we conducted a spatial analysis of the feed industry. We used data from 629 BSE cases as well as data on use of each byproduct and market area of the feed factories. We mapped risk for BSE in 951 areas supplied by the same factories and connection with use of byproducts. A disease map of BSE with covariates was built with the hierarchical Bayesian modeling methods, based on Poisson distribution with spatial smoothing. Only use of MBM was spatially linked to risk for BSE, which highlights cross-contamination as the most probable source of infection after the feed ban. In France, meat-and-bone meal (MBM) has been banned from cattle feed since July 30, 1990. However, through January 1, 2007, 957 cases of bovine spongiform encephalopathy (BSE) have been detected in cattle born after the ban. These cases provide evidence that BSE control has not been entirely effective, which poses a concern because BSE is a zoonotic disease, a source of variant CreutzfeldtJakob disease (vCJD). Until now, 158 defi nite or probable cases of vCJD in humans have been detected in the United Kingdom (www.cjd.ed.ac.uk/fi gures.htm, consulted March 12, 2007) and 21 in France (www.invs.sante.fr/recherche, consulted March 12, 2007). The risk for humans is controlled by removing specifi ed risk materials from human consumption (since 1996 in France, later in other European countries) and testing all cattle at the abattoir with a rapid test (since 2001 in continental European Union). However, these measures are expensive. Achieving 100% control of the spread of BSE is a major challenge, important for human health but limited by economic constraints.The main hypothesis concerning the source of infection in cattle born after the MBM ban still involves MBM; the BSE agent may have entered cattle feed by cross-contamination with feed for monogastric species (pigs and poultry) in which MBM was still authorized until November 2000. Cross-contamination could have occurred within factories, during feed delivery to the farm, or on mixed farms that have cattle and pigs or poultry. This hypothesis is supported by the fi nding of MBM traces in cattle feed (1) as well as by epidemiologic studies that showed a spatial link between density of monogastric species and risk for BSE (2-7).Another hypothesis, however, suggests the role of other animal byproducts such as fat and dicalcium phosphate (DCP) derived from bones, which were not prohibited in cattle feed before 2000. Such components might have been contaminated by the BSE agent during cattle slaughter (1). Clauss et al. (5) found a statistically higher use of milk replacers (which contain animal fat) for calves on BSE-affected farms in Germany, and the same type of association was observed in France for scrapie in sheep (8).More knowledge about...

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Bovine Spongiform Encephalopathy and Spatial Analysis of the Feed Industry

Paul¹,

Abrial²,

Jarrige

et al. 2007

Emerg. Infect. Dis.

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“…Further evidence on the BAB cases arising from the feedborne source has been provided by Sheridan et al [57], where a spatial relationship between feed-producers and BSE cases was found. Recently, a case-control study [42] evidenced the use of feed from feedstuff factories fed to young cattle as well as the existence of poultry operation in the farm, if using compound feed, as risk factors for BSE, and thus reinforced the role of compound feed in the risk of BSE.…”

Section: Routes Of Infectionmentioning

confidence: 99%

“…In Germany, milk replacers could legally contain animal-derived fats until 2000, and it is possible that either infectious material survived the rendering process or that infectious material entered milk replacers through the use of unrefined fats, which were used in milk replacers in Germany [43]. Pottgiesser et al [52] have also shown a possible association of the feeding of milk replacers with BSE infection in the Schleswig-Holstein region of Germany; the use of milk replacer was also found to be a risk factor in France [42], and they have been suggested as a potential route of infection in Denmark, where Paisley and Hostrup-Pedersen [50] showed that tallow-based milk replacers could have been responsible for all seven cases of BSE in this country. However, there is no experimental evidence to show that tallow from an infected cow contains infectivity, and so the link between milk replacers and BSE infection remains a hypothesis.…”

Section: Routes Of Infectionmentioning

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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“…A possible causal association between the feeding of potentially contaminated milk replacers to calves and the occurrence of BSE has been suggested by several epidemiologic studies (2)(3)(4)(5). However, no report shows experimental transmission of BSE by use of tallow or milk replacers (6).…”

Section: Milk Replacers and Bovine Spongiform Encephalopathy Inmentioning

confidence: 99%