Brain and spinal cord (central nervous system tissue) of cattle can transfer bovine spongiform encephalopathy (BSE) to humans. BSE is expressed in humans as a lethal spongiform encephalopathy which was first detected in 1995 as a new variant of Creutzfeldt-Jakob disease (vCJD). More than 95% of BSE-causing agents are concentrated in the central nervous system (CNS: brain and spinal cord) and in specific areas of the peripheral nervous system near the spinal cord, known as dorsal root ganglia.
Consequently, in 1997 the Commission of the European Community decided on the strict prohibition of specified risk material (SRM) from the human food chain (97/534/EC) as the primary and most effective step to protect consumers from BSE-causing agents. The specification of the risk material is mainly focused on the brain and spinal cord of cattle, sheep and goats over 12 months old.
However there is mounting scientific evidence that argues against a restriction by age or species. In addition, it has been shown in animal models that so called “resistant” species can multiply and transmit infective agents of transmissible spongiform encephalopathies (TSE′s) without catching the disease. This indicates that CNS of animal species which have not previously been subjected to testing, but which have come into contact with BSE-causing agents via animal feed, should be generally categorised as risk material.
The German Institute for the Protection of Consumer Health and Veterinary Medicine (BgVV) concluded in their statement of 25.04.2002 that using current slaughter practices the contamination of meat with tissues that can already show the highest BSE infectivity is unavoidable. Similarly, the European Union BSE / TSE ad hoc Group concluded in the “Scientific Report on Stunning Methods and BSE Risk” of 13.12.01 (Download) that penetrative stunning can lead to a risk of contamination with CNS tissue.
Therefore, it makes sense to test the outer surfaces of meat, particularly from the head, for contamination with CNS tissue. To test the hygiene of slaughter it can be useful to check knives and other surfaces that were, or might have been, in contact with the CNS for contamination with CNS tissue.
According to EC Regulation 1139/2003, slaughterhouses that use heads of bovine animals have to use an appropriate laboratory test to detect CNS tissue.