title: A comparison of the risk of bovine spongiform encephalopathy infectivity in beef from cattle younger than 21 months in Japan with that in beef from the United States as assessed by the carcass maturity score.
abstract: After the detection of the first case of bovine spongiform encephalopathy (BSE) in the United States in December 2003, the Japanese government halted all imports of U.S. beef. The BSE risk in beef is partly dependent on the slaughter age of the cattle from which it is derived. In Japan, all cattle 21 months old and older are screened using a rapid diagnostic test, while in the United States, routine BSE testing is not done at any age of slaughter cattle. In the United States, there is no nationally mandated cattle identification system that enables cattle younger than 21 months to be identified. Therefore, all beef potentially produced for export to Japan must be from cattle that are age verified as younger than 21 months old or be classified by the U.S. Department of Agriculture using a carcass maturity score, which in turn is related to the age of the animal from which the beef is derived. After consulting the Food Safety Commission, the Japanese government decided on 12 December 2005 to allow importation of beef from the United States derived from cattle with a carcass maturity score of < or =A40 and from which specified risk materials are removed. In this study, a stochastic model was used to simulate the interval of time from slaughter to the predicted clinical onset of BSE in an infected animal. A simulation result, based on the assumption that the BSE prevalence is equivalent in the two countries, revealed that there was no increased risk of BSE infectivity in beef coming from carcasses with a maturity score of < or =A40 in the United States, compared with beef from cattle younger than 21 months slaughtered in Japan.
authors.affiliation: Food and Agricultural Materials Inspection Center, 2-1 Shintoshin, Chuo-ku, Saitama-shi, Saitama-prefecture, 330-9731 Japan. katsuaki_sugiura@nm.famic.go.jp
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Sugiura
authors.forename: Gary C
authors.initials: GC
authors.lastname: Smith
mesh_terms: D000367:Age Factors; D000823:Animal Identification Systems; D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D003257:Consumer Product Safety; D016643:Encephalopathy, Bovine Spongiform / Q000635:transmission*; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D007564:Japan; D008403:Mass Screening; D008460:Meat / Q000032:analysis*; D018570:Risk Assessment; D013269:Stochastic Processes; D014481:United States