Further characterisation of transmissible spongiform encephalopathy phenotypes after inoculation of cattle with two temporally separated sources of sheep scrapie from Great Britain.

Background: The infectious agent responsible for the bovine spongiform encephalopathy (BSE) epidemic in Great Britain is a transmissible spongiform encephalopathy (TSE) strain with uniform properties but the origin of this strain remains unknown. Based on the hypothesis that classical BSE may have been caused by a TSE strain present in sheep, cattle were inoculated intracerebrally with two different pools of brains from scrapie-affected sheep sourced prior to and during the BSE epidemic to investigate resulting disease phenotypes and characterise their causal agents by transmission to rodents.

Results: As reported in 2006, intracerebral inoculation of cattle with pre-1975 and post-1990 scrapie brain pools produced two distinct disease phenotypes, which were unlike classical BSE.

Bovine spongiform encephalopathy: the effect of oral exposure dose on attack rate and incubation period in cattle - an update.

Background: To provide information on dose-response and aid in modelling the exposure dynamics of the BSE epidemic in the United Kingdom groups of cattle were exposed orally to a range of different doses of brainstem homogenate of known infectious titre from clinical cases of classical bovine spongiform encephalopathy (BSE). Interim data from this study was published in 2007. This communication documents additional BSE cases, which occurred subsequently, examines possible influence of the bovine prion protein gene on disease incidence and revises estimates of effective oral exposure.

Case-control study of cases of bovine spongiform encephalopathy born after July 31, 1996 (BARB cases) in Great Britain.

This paper reports the results of a case-control study of the bovine spongiform encephalopathy (BSE) cases born in Great Britain after the statutory reinforcement of the ban (BARB) on the feeding of mammalian-derived meat and bone meal on 31 July 1996. A total of 499 suspect clinical cases of BSE, born after 31 July 1996, and reported negative by July 31, 1996 and were compared with the set of 164 confirmed Great BARB cases in Great Britain detected by both passive and active surveillance. Animal-level risk factors (age and type of feed offered) and herd-level risk factors (herd size and type, number of prereinforced feed ban BSE cases born on the holding, the presence of other domestic species and waste management) were obtained for the analysis.

Descriptive epidemiological features of cases of bovine spongiform encephalopathy born after July 31, 1996 in Great Britain.

This paper describes the results of analyses of the epidemiological features of the 164 cases of bovine spongiform encephalopathy (BSE) in Great Britain that were born after the introduction of the reinforced legislation introduced on August 1, 1996 (BARB cases) and that were detected before December 31, 2008. This additional control measure prohibited the use of mammalian meat and bone meal (MMBM) in feed for farm animals to prevent further exposure of cattle to the BSE agent. There was a pronounced reduction in the risk of infection, by three orders of magnitude, for cattle born after July 31, 1996 compared with that for cattle born earlier, and a statistically significant exponential reduction in the estimated prevalence between successive annual birth cohorts after this date.