Risk management of transmissible spongiform encephalopathies in Europe

Abstract

Bovine spongiform encephalopathy (BSE) was first described in the United Kingdom (UK) in November 1986. After the introduction of an active surveillance system, most countries in Europe have reported BSE cases in the cattle population. This indicates that the use of active surveillance in addition to passive surveillance is important to assess the true BSE status in a country. Scrapie, a transmissible spongiform encephalopathy (TSE) in sheep and goats, has been reported in countries throughout the world with a few notable exceptions. Concern was expressed that BSE could have been introduced into sheep and goats. Currently, distinguishing between scrapie and BSE in small ruminants is only possible through lengthy experiments in mice. Preliminary results of active surveillance, introduced in 2002, show that significant under-reporting occurred. The history of BSE in cattle shows that risk assessments concerning the risk in a given country were often ignored and subsequent risk management decisions were inaccurate, i.e. although the risk was probable, no measures were taken in terms of either animal or human health. Furthermore, the effect of the measures taken was often overestimated and these had to be amended several times. The most important action to prevent new cases of TSEs occurring is by banning the feeding meat-and-bone meal (MBM) to ruminants. Further measures to be considered are the exclusion of specified risk material and carcasses from rendering, the process parameters for rendering of animal waste and the prevention of cross-contamination of feed with MBM. The most important measures to protect the consumer are the ban on specified risk material, such as brain and spinal cord, which may contain particularly high concentrations of the BSE agent, and the ban on mechanically recovered meat. The most important measures taken in Europe and the scientific background thereof are described and discussed.