Epidemiology of bovine spongiform encephalopathy in cattle in Hokkaido, Japan, between September 2001 and December 2006

Abstract

Between October 2001 and December 2006 an estimated total of 6 million cattle in Japan were tested for BSE, with 31 returning a positive result. Exploratory mapping, the space-time scan statistic, and ordinal logistic regression have been used to describe the epidemiology of the 24 cases identified in the prefecture of Hokkaido, and to quantify the risk factors for the disease. Two birth cohort groups were affected: cattle bom during a period of seven months in 1996, and cattle born between 1999 and 2001. The descriptive spatial analyses showed that eight of the 10 cases born in 1996 were born in areas with a relatively high density of dairy farms in the east of Hokkaido, but that the 14 lat..