The Topographic distribution pattern of vacuolation in the central nervous system of cattle infected orally with bovine spongiform encephalopathy

Abstract

Bovine spongiform encephalopathy (BSE) is a scrapie-like disease of cattle first recognized in the United Kingdom in 1986. The predominant pathology is a vacuolar degeneration of the central nervous system. In naturally affected cattle the severity and distribution of these vacuolar changes present an almost invariable pattern. The source of infection responsible for the current epidemic is considered to be commercially processed feed contaminated with a scrapie-like pathogen. A foodborne source of infection is also considered the likely origin of scrapie-like disease in other mammalian species, including the domestic cat and several species of exotic bovids and felids in zoological collections, which have occurred contemporaneously with the BSE epidemic. In common with other scrapie-like diseases BSE has been transmitted experimentally to several other species. The transmission of BSE to cattle by the oral dosing of calves with BSE-affected brain stem homogenate has been reported previously. Histopathological examinations of the brain based on the lesion profile system, developed originally for the characterization of scrapie in laboratory mice, were used to examine the distribution and severity of vacuolar changes in these cattle. The results were compared with the vacuolar profile in naturally affected cattle. The distribution of vacuolar changes in cattle dosed orally with BSE closely resembles that observed in naturally affected cattle providing experimental evidence that this route closely simulates natural infection and subsequent neural pathogenesis.