Simulation-based estimation of BSE infection in Japan

A Quantitative Risk Assessment for Bovine Spongiform Encephalopathy in Japan

“…These authors concluded that MBM imported into Japan from 1996 to 1998 was the most important factor influencing the risk of release of the BSE agent into Japan. Yamamoto et al ( 14 ) developed a model to simulate the year and final dispositions of infected cows in birth cohorts of Japanese cattle, concluding that 1996‐born Japanese cattle were a source of infection for cattle born between 1999 and 2001; findings consistent with those of Kadohira et al ( 15 ) in an analysis of the 24 cases of BSE born in Hokkaido reported up to December 2006. Sugiura et al ( 5 ) used records of the number of live animals imported into Japan during the 1980s as an estimate of external challenge and concluded that the 1996 administrative guidelines on the use of MBM were effective in reducing the amount of MBM fed to cattle by a factor of between 104 to 141.…”

“…A number of models have been developed for the epidemic of BSE in Japan in addition to the analyses presented in this article. ( 5,13,14,32,33 ) The models described by Sugiura and Murray ( 32 ) used Bayesian inference to provide an estimate of the prevalence of BSE infection among birth cohorts of Japanese cattle. Assuming that infection entered the feed chain in either 1992 or 1995 and that no more animals became infected from the beginning of 2002 these authors predicted that between zero and two cases of BSE would be detected in Japan after 2009 and that BSE would be eradicated by 2012.…”

“…Assuming that infection entered the feed chain in either 1992 or 1995 and that no more animals became infected from the beginning of 2002 these authors predicted that between zero and two cases of BSE would be detected in Japan after 2009 and that BSE would be eradicated by 2012. Yamamoto et al ( 14 ) developed a simulation model to estimate the year of death and final disposition of infected cows born in each year from 1996 to 2001 as a means for estimating the number of infected stock that were slaughtered for human consumption. These authors estimated that between 90 and 275 1996‐born cattle were infected.…”

“…Of this group, 56 died or were slaughtered before October 2001 after accumulation of infectious agent in their bodies and only five of these 56 cattle were estimated to have been slaughtered for human consumption. Yamamoto et al ( 14 ) concluded that the number of infected cattle that could have served as a source of human infection was a limited subset of the total number of BSE‐infected cattle in Japan.…”

Target cattle age of post-slaughter testing for bovine spongiform encephalopathy and infectivity entering the human food chain in Japan

“…Differences in breeding area, farming practices, or feedstuff were also pointed out. (Yamamoto, Tsutsui, Nishiguchi, & Kobayashi, 2008;Yoshikawa, 2008). Therefore, sex and breed difference may be the key factor affecting food safety, and should be taken into consideration for the assessment of the BSE testing.…”