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BSE in France: demonstration of the role of meat and bone meal used in feed for monogastric animals
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Press Info item.
22/06/2007
BSE in France: demonstration of the role of meat and bone meal used in feed for monogastric animals
INRA researchers, in collaboration with AFSSA, have performed a spatial analysis to study the sources of contamination by the bovine spongiform encephalopathy (BSE) agent in France, related to the use in animal feed factories of meat and bone meal (MBM) for monogastric animals, animal fats and dicalcium phosphate precipitated from bones. This study concerned the period 1990-2000, during which MBM was banned from cattle feed but still authorised in feed for monogastric animals (pigs, rabbits, poultry). The results demonstrate the importance of using MBM to produce feed for monogastric animals (pigs, rabbits, poultry) to the existence of BSE-affected animals born after 1990.
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A spatial analysis was performed to study possible sources of contamination by the BSE agent in France following the ban on meat and bone meal (MBM) from cattle feed in 1990, and related to using MBM in feed for monogastric animals, as well as animal fats and phosphates precipitated from bones. The hypotheses concerned cross-contamination between feed for monogastric animals (in which MBM were authorised until 2000) and feed for cattle, as well as the BSE contamination of animal by-products used at the time in cattle feed (fats, phosphates).
The different stages in the analysis
The data concerned the 629 animals with BSE born in France after the ban on using MBM for cattle feed (July 1990) and detected between July 2001 and December 20051. As a reminder, the period of birth broadly corresponds to the period when animals are contaminated; cases are usually detected 4 to 8 years after contamination. Data on 327 cattle feed factories were collected by departmental veterinary services.
The first stage consisted in defining the supply zones common to a group of factories and deemed homogeneous regarding the contamination hypotheses considered. The incidence of BSE cases was studied for the 951 zones thus obtained, as was the proportion of factories using each of the three by-products between 1990 et 2000.
cf. map►
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The next stage was to analyse the links existing between the incidence of BSE in these zones and the frequency of use of each of the three by-products by factories supplying the zones.
The final stage consisted in the mapping of BSE cases based on a hierarchical Bayesian model (Poisson model with spatial smoothing and explanatory variables linked to the three hypotheses studied).
The role of cross-contamination between feeds was demonstrated
The results demonstrated the probable role in BSE contamination between 1990 and 2000 of the use in MBM by factories to produce feed for monogastric animals. However, no statistical link was observed with the use of animal fats or phosphates.
These results thus confirmed the importance of cross contaminations between feeds for monogastric animals and cattle as being the most probable source of infection in BSE-affected animals born after the ban on MBM in cattle feed. This analysis supplements and confirms the results of the case-control study performed by AFSSA in collaboration with INRA concerning the same problem (cf. reference below).
What precautions are necessary for the future?
Only one case of BSE (born on January 1st 2001) has been detected to date in France amongst animals born after November 2000, the date when the total ban on MBM and different animal products was implemented with respect to feed for animals intended for human consumption. The current situation in France is extremely favourable and appears to be under control. This should enable a gradual lifting of certain surveillance and control measures with respect to BSE. In this very optimistic setting, the results of our study and the parallel case-control study nonetheless constitute a warning as to the risk of a re-emergence of this disease, which could result from re-authorising the use of MBM in feed for monogastric species without any drastic measures being in place to control the risk of cross contamination between feeds for monogastrics and cattle, not only in cattle feed factories but also on farms.
1 For information, 11 other cases of BSE have been detected in France since January 2006; none of these animals was born after January 1st 2001 (http://www.agriculture.gouv.fr/esbinfo/esbinfo.htm , consulté le 06/06/07)
References:
“Bovine Spongiform Encephalopathy and Spatial Analysis of the Feed Industry”
Paul M*, Abrial D*, Jarrige N†, Rican S‡, Garrido M*, Calavas D†, Ducrot C*
Emerging Infectious Diseases, 2007, 13 (6) 867-872, June 2007.
*Institut National de la Recherche Agronomique (INRA), Saint Genès Champanelle, France;
†Agence Française de Sécurité Sanitaire des Aliments (AFSSA), Lyon, France;
‡Université Nanterre Paris X, Paris, France
http://www.cdc.gov/eid/content/13/6/867.htm
"Case-control study on feed risk factors for BSE cases born after the feed ban in France"
Nathalie Jarrige*, Christian Ducrot †, Géraldine Cazeau*, Eric Morignat*, Claude La Bonnardière †, Didier Calavas*
Veterinary Research, 2007, 38, 505-516.
* Agence Française de Sécurité Sanitaire des Aliments (AFSSA), Lyon, France,
† Institut National de la Recherche Agronomique (INRA), Saint Genès Champanelle, France.
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Written by :
INRA press service, phone: +33 (0)1 42 75 91 69
Contacts :
Christian DUCROT
Tel.: 04 73 62 42 63
christian.ducrot@clermont.inra.fr
Animal Epidemiology Research Unit,
Animal Health Division,
Clermont-Ferrand-Theix Research Centre
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