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Risk of Introduction of BSE into Japan from U.K. imports ...

flounder

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Journal of Veterinary Medical Science


Vol. 71 (2009) , No. 2 February pp.133-138



Risk of Introduction of BSE into Japan by the Historical Importation of Live Cattle from the United Kingdom


Katsuaki SUGIURA1), Toyoko KUSAMA1), Tomotaro YOSHIDA1), Naoki SHINODA1) and Takashi ONODERA2)

1) Food and Agricultural Materials Inspection Center 2) Department of Molecular Immunology, University of Tokyo

(Received 10-Mar-2008) (Accepted 3-Sep-2008)

ABSTRACT. All cattle imported from the United Kingdom to Japan since 1980 and slaughtered before 2002 were traced (n=33), and the number of cattle that were possibly infected with BSE and entered the animal feed chain was calculated. Because there was no effective system to avoid recycling of the BSE agent via animal feed until the early 1990s, of the 33 cattle imported from the UK into Japan, most probably 7 or 8 were infected and entered the animal feed chain, 2 of which entered the animal feed chain in each of 1992 and 1993. In terms of infectivity, 400-550 cattle oral ID50 of the BSE agent entered the feed chain in each of these years. The amount of infectivity that entered the feed chain in 1989, 1991 and 1995 was smaller but still substantial, suggesting that the BSE agent might have entered the Japanese feed chain in any of these years.

KEY WORDS: bovine spongiform encephalopathy (BSE), import risk analysis, Japan, live cattle, simulation



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DISCUSSION AND CONCLUSION


The results of this study indicate that, if BSE had been introduced into Japan by live cattle imported from the UK, it would have most probably entered Japan through cattle imported in 1987 and 1988 and that infectivity would then have been most likely introduced into the feed system through MBM produced from carcasses or waste materials from one or more of these cattle when they were slaughtered or died during 1992–1993. This is consistent with the results of Sugiura’s previous study reported in 2004 [11].


The results of this study also indicate that a substantial amount of BSE infectivity is likely to have been released into the feed chain by imported cattle from the UK in 1992 and 1993, and a small but still substantial amount of BSE infectivity is likely to have been released in 1989, 1991 and 1995. Considering the amount of infectivity that entered the feed chain and the absence of a cattle/BSE system that would avoid processing of infected cattle and recycling the BSE agent via the feed chain (SRM removal, pressurized heat treatment of MBM, and an effective feed ban were not practiced or in place), one can assume that some Japanese cattle born in the early 1990s became infected by consuming contaminated MBM produced from these imported cattle.


Of the 35 BSE cases detected in Japan by the end of April 2008, 13 were born in 1995–1996, 19 were born in 1999– 2001, two were born in 1992 and one was born in 2002. Considering the substantial amount of infectivity that entered the feed chain in 1989, 1992, 1993 and 1995 and that cattle get infected within one year of birth [17], the cases born in 1995–1996 might have been infected by consuming feed containing infected MBM produced in 1995 or by recycling of cattle infected in 1989–1993. Of the two BSE cases born in 1992, one was atypical, and the other was typical, which might have been infected by consuming feed containing infected MBM produced in 1991–1993.


The results of the present study are consistent with the conclusion made by Yoshikawa et al. in their report [18], that the imported cattle from the UK that were slaughtered in an abattoir in the Kanto region in 1995 and whose rendered byproducts were used in that region, possibly became the source of infection for the three BSE cases detected in this region.


In Sugiura’s previous study [11], only the cattle that developed BSE (i.e., had reached the last stage of the incubation period) were assumed to be infectious. As a result, the probabilities that BSE entered the animal feed chain might have been underestimated. The present study has overcome this problem by using prevalence of infection (probability of being infected) instead of using incidence rate (probability of developing clinical signs) for each birth cohort.


In the present study, we assumed that the cattle imported from the UK all died or were slaughtered for non-BSE reasons because according to the official records, none of them showed clinical signs compatible with BSE at death/slaughter. However, most of the 33 animals had some clinical signs at death/slaughter, such as reproductive disorder, arthritis, mastitis, post-parturition downer, ketosis, rumen displacement [18], and some of them might have died or been culled after having completed the incubation period. As a result, the amount of infectivity that entered the animal feed chain might have been underestimated.


According to the Ministry of Agriculture, Forestry and Fisheries’ database [18], the amount of MBM used between 1989 and 1995 as raw material for the production of cattle compound feed was 83 to 247 metric tons annually, representing less than 0.05% of the total amount of MBM used for feed (most of the MBM used for feed was used for production chicken and pig feed). In addition, co-farming of ruminants and non-ruminants is not a common practice in Japan. These facts suggest that, of the 1,080–1,460 cattle oral ID50 that were estimated to have entered the animal feed chain between 1989 and 1995, the amount of BSE agent consumed by cattle would be much smaller, and thus the amount of BSE agent estimated should be considered the maximum amount consumed by cattle. Considering that the BSE agent is likely to be heterogeneously distributed in feedstuffs [16] and that no information was available about how heterogeneously the BSE agent was distributed in feed in Japan, the authors suggest that, without calculating the possible number of infected animals, the calculated amount of ID50 represents the maximum amount that would have been consumed by cattle.



Fig. 2. Probability distributions of the number of infected animals that entered the animal feed chain from (a) the total of 33 cattle imported from the UK, (b) the 5 cattle imported from the UK in 1982, (c) the 9 cattle imported from the UK in 1987 and (d) the 19 cattle imported from the UK in 1988.



Fig. 4. Amount of BSE infectivity that entered the animal feed chain in Japan by year. Solid, dashed and dotted lines assume doubling time of 4 months, 2 months and 1 month, respectively


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http://www.jstage.jst.go.jp/article/jvms/71/2/133/_pdf


REFERENCES


http://www.jstage.jst.go.jp/article/jvms/71/2/71_133/_cit




Greetings BSE-L members !



>>>Because there was no effective system to avoid recycling of the BSE agent via animal feed until the early 1990s, of the 33 cattle imported from the UK into Japan, most probably 7 or 8 were infected and entered the animal feed chain, 2 of which entered the animal feed chain in each of 1992 and 1993. In terms of infectivity, 400-550 cattle oral ID50 of the BSE agent entered the feed chain in each of these years. The amount of infectivity that entered the feed chain in 1989, 1991 and 1995 was smaller but still substantial, suggesting that the BSE agent might have entered the Japanese feed chain in any of these years.<<<



O.K., lets look at other imports of live catte from the U.K. to the U.S.A. and Canada, just to compare to Japan.


UK Exports of Live Cattle by Value 1986-96

USA 697 LIVE CATTLE

CANADA 299 LIVE CATTLE



SO, where does that leave us here in North America ???


HERE IN THE U.S.A. IT'S WHAT I CALL, MAD COW DENIAL $$$



TSS


USA AND CANADA IMPORTS OF UK CATTLE BETWEEN 1981 - 1989


USA = 496

CANADA = 198

*add 14 to 198 as last UK import to Canada, 14 in 1990

http://www.inspection.gc.ca/english/sci/ahra/bseris/bserise.pdf



HERE is another look at all the imports for both the USA and Canada of UK live cattle and greaves exports ;


UK Exports of Live Cattle by Value 1986-96

USA 697 LIVE CATTLE

CANADA 299 LIVE CATTLE

http://www.bseinquiry.gov.uk/files/mb/m11f/tab11.pdf



UK EXPORTS OF MBM TO WORLD

http://www.bseinquiry.gov.uk/files/mb/m11g/tab05.pdf


OTHERS



SNIP...



*** SEE FULL TEXT ;


Risk of Introduction of BSE into Japan by the Historical Importation of Live Cattle from the United Kingdom


http://bseusa.blogspot.com/2009/03/risk-of-introduction-of-bse-into-japan.html



TSS
 

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