Comparison and verification of BSE surveillance in USA and Japan

The objectives of this study are to (1) compare the BSE surveillance systems of Japan and the United States (US), and to (2) validate the US enhanced BSE Surveillance program.

This study compares the BSE surveillance systems in Japan and the US, specifically focusing on the procedures of initial test, diagnosis and confirmation. The study further examines the validity of statistical conclusions made in the US enhanced surveillance program based on the data collected from the BSE inspection performed by the Ministry of Health, Labor and Welfare of Japan (MHLW) and the Ministry of Agriculture, Forestry and Fisheries of Japan (MAFF) between October 18,2001 and July 31, 2004. The inspection targeted all slaughtered healthy and high risk cattle.

The US enhanced surveillance program assumes no BSE occurrence in the normal adult cattle population and thus its inspection focuses only on high risk cattle. The BSE inspection performed in Japan, however, revealed that 0.00022% of the normal adult cattle were BSE-infected using the US criteria. Assuming that the same ratio of cattle was BSE-infected in the US, the Japan finding indicates that approximately 30% of the US slaughtered normal cattle population aged 30 months and over needs to be tested to satisfy the statistical condition used by the US (i.e., 99% confidence level). On the other hand, in order for Japan to perform the surveillance with a 99% confidence level (the statistical condition used by US), Japan needs inspect: (1) 60,539 high risk cattle (i.e., 60% of 100,583 high risk cattle); (2) 78% of normal adult cattle aged 30 months and over (1,088,589/1,387,522) and (3) 90% of normal cattle aged 30 months or less (1,845,138/2,050,154).

The US enhanced surveillance program launched in July 2004 is based on the premise that no BSE occurs in normal adult cattle population. In Japan, however, BSE cases satisfying the US criteria have been found among the normal adult cattle. This fact suggests that the US needs to consider inspections targeting the normal adult cattle. This fact suggests that the US needs to consider inspections targeting the normal adult cattle in the future. At the same time, for more efficient surveillance, Japan may need to consider BSE inspections targeting the high risk cattle population with a higher confidence level and normal adult cattle with a lower confidence level.