Analysis of the Bovine Spongiform Encephalopathy Maternal Cohort Study: the Discordant Case–Control Pairs

The progeny of the affected and non-affected dams in the bovine spongiform encephalopathy (BSE) cohort study were paired in terms of their farm of origin and approximate date of birth. This paper presents an exact logistic regression analysis that avoids modelling the differences between the pairs and so analyses only the discordant pairs. There is some evidence that the pairs in which the affected animal was born to the affected dam tend to be those in which the onset of BSE in the affected dam preceded or occurred soon after the calving. This suggests some occurrence of maternal transmission.