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12 Bovine Spongiform Encephalopathy and Related Diseases

Gerald A. H. Wells, John W. Wilesmith


In November 1986, at the Veterinary Laboratories Agency, Weybridge, United Kingdom (formerly the Central Veterinary Laboratory), the routine histopathological examination of the brains of three cows from dairy farms in southern England was the critical juncture in the recognition of a new neurologic disease of cattle, subsequently termed bovine spongiform encephalopathy (BSE). The neurohistological changes observed bore a striking resemblance to those of scrapie of sheep, the historic archetype of the transmissible spongiform encephalopathies (TSEs) (Wells et al. 1987). Important in the confirmation of this diagnostic discovery were not only the characteristic pathological changes in the brain, but also the individual case histories, which included details of the clinical signs of the disorder provided by veterinarians (Wells et al. 1987Wells et al. 1992; Wells 1989). Clinically, there was the insidious onset of altered behavior (apprehension and sometimes, aggressive responses), ataxia (uncoordinated gait with falling), and dysesthesia or reflex hyperesthesia (abnormal responses to touch and sound). In retrospect, clinical cases of BSE were seen in England in 1985, but probably not before that year (Bradley 2001). The relentlessly progressive and prolonged course (1–6 months) of the signs made affected animals impossible to handle, necessitating their slaughter (Wilesmith et al. 1988). Through 1987, further cases were diagnosed in Great Britain and the number of cases continued to increase each month, indicating the onset of a major epidemic (Fig. 1). The new disease, BSE (Wells et al. 1987), was made statutorily notifiable in June, 1988 (Anonymous 1996a;Wilesmith 1996a).

The many aspects of BSE, including...

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