Bovine Spongiform Encephalopathy (BSE) in bovine animals
Bovine Spongiform Encephalopathy (BSE) is a TSE disease of cattle. BSE was first diagnosed in the UK in 1986, and reached epidemic proportions due to cattle being fed with processed animal protein, produced from ruminant carcasses, some of which were infected. The common symptoms of BSE include behavioural changes, lack of coordination, difficulty in walking or standing up, decreased milk production and weight loss. However, the disease has also been detected in animals showing no symptoms or atypical signs of the disease. The average incubation period of BSE in cattle is 4-6 years, but it can be much longer. BSE is considered to be transmissible to humans. Please refer to vCJD, below.
Nowadays, two forms of BSE are distinguished: Classical BSE, which is transmitted via the feed and was the cause of the BSE epidemics in the 80s, 90s and 2000s; and Atypical BSE (with 2 types of Atypical BSE: the L-type and the H-type), which is considered to be a spontaneous and sporadic disease, not linked to the feed given the animals, occurring at a very low prevalence rate in old bovine animals.
TSEs in sheep and goats
Scrapie is a TSE in small ruminants (sheep and goats) and it can be divided into classical scrapie and atypical scrapie. First recognised more than 250 years ago, it has been known for centuries. It is assumed that scrapie can be transmitted horizontally, from one animal to another or via environmental routes, or vertically, from ewe to lamb / from goat to kid. The clinical signs of scrapie are found predominantly in animals aged from 2 to 5 years and include weight loss, salivation, pruritus and associated hair loss and skin abrasions, incoordination of hind limbs and altered behaviour such as observed nervousness, depression, excitability or aggressiveness. On the basis of the available scientific data scrapie is not considered to be transmissible to humans.
BSE has once been detected in a goat in the EU wide surveillance programmeBSE has once been detected in a goat in the EU wide surveillance programme designed to detect suspicious TSE strains in sheep and goats. The case was confirmed in January 2005 by the EU Reference Laboratory (EURL) for TSEs and it concerned a goat slaughtered in France in 2002. The goat was disposed of after slaughtering as well as its entire herd and did not enter the food chain. In addition, retrospective testing of a Scottish goat culled in 1990s gave results indicative of BSE and the EURL for TSEs concluded in May 2009 that BSE cannot be excluded. Following the French BSE case detected in a goat, the European Commission advised no change in the current consumption of goat milk, cheese and meat. EU food safety rules ensure that only products from healthy animals are allowed to enter the food chain and the food placed on the market is safe. As an additional safety measure the specified risk material (the tissues most likely to carry infectivity if TSE is present) are also removed from all goats. Since then, no other case of BSE have been detected in goats. Furthermore, BSE has never been detected in sheep.
Chronic Wasting Disease (CWD)
Chronic Wasting Disease (CWD) is a TSE disease of cervids (deer, elk and moose). The symptoms of CWD are a loss of body condition ("wasting") and behavioural abnormalities such as staggering and poor standing posture. CWD has never been detected in Europe, but is quite common in North America (USA and Canada) and has been detected in Norway for the first time in April 2016. Though CWD belongs to the same family as BSE and scrapie, there is no known relationship between CWD and other TSEs in animals or humans under natural conditions.
Variant Creutzfeldt-Jakob Disease (vCJD)
Variant Creutzfeldt-Jacob Disease (vCJD) is a TSE disease in humans. vCJD was first diagnosed in 1996. It is now generally assumed to be caused by the transmission of the BSE agent to humans by the oral route. vCJD occurs mostly in young people and most cases have occurred in the UK, although there have been cases also in France, Ireland, Italy, the Netherlands, Portugal and Spain in the EU and in the USA, Canada, Saudi-Arabia, Taiwan and Japan in non-EU countries. So far 220 vCJD cases have been detected in the EU (177 in the UK), and 9 cases outside the EU. At present the cCJD epidemic seems to be vanishing.
The Commission introduced the first EU legislation on BSE in July 1989. By the middle of 1990, basic EU legislation on BSE was in place concerning meat and live cattle. Today, Regulation (EC) No 999/2001 (" the TSE Regulation") forms the legal basis for almost all legislative actions on TSEs. It gathers together all BSE measures adopted over the years into a single, comprehensive framework consolidating and updating them in line with scientific evidence and international standards. It has been amended many times in response to the evolution of the BSE situation, new or updated scientific advice and/or technological developments. The purpose of the TSE legislation is to protect the health of consumers and animals and to control and eradicate TSEs. In addition, according to the EU hygiene legislation (Regulation (EC) No 854/2004), all animals presented for slaughter must undergo a veterinary inspection (ante mortem) to ensure that suspected cases do not enter the food and feed chain.
The main provisions of the TSE Regulation can be summarised as follows:
Since May 1998, EU-wide measures on surveillance have been in place. See Annexes III and X to the TSE Regulation. See topics Monitoring and Diagnostics
The feed ban is the basic preventive measure laid down against BSE and consists of a ban on the use of processed animal protein (PAP) in feed for farmed animals. PAP produced from infected ruminants is assumed to be the transmission route of BSE. See Annex IV to the TSE Regulation. See topic Feed Ban
Specified risk material
Another equally important preventive measure is the removal of Specified Risk Material (SRM) from cattle, sheep and goats so it doesn't enter the food and feed chain (since October 2000). SRM are the tissues where BSE infectivity is most likely to occur. The list of SRM to be removed for bovine animals depends on the BSE risk status of the country of origin. See Annex V to the TSE Regulation, where SRM for both bovine animals and for ovine and caprine animals are listed in detail.
Determination of BSE status: Classification
The BSE status of Member States or third countries or regions thereof is to be determined by classification into one of three categories depending on the BSE risk involved: a negligible risk, a controlled risk and an undetermined risk. This classification is based on that of the World Organisation for Animal Health (OIE) since July 2007, and is laid down in Commission Decision 2007/453/EC, which is regularly amended. The BSE status of EU Member States and neighbouring countries according to Commission Decision 2007/453/EC as last amended is summarised on the linked map.
Member States may introduce breeding programmes to select for resistance to TSEs in their ovine populations. It has been shown that sheep of a certain genotype are more resistant to scrapie. See Annex VII to the TSE Regulation.
Control and Eradication of TSEs
The TSE Regulation lays down culling and eradication measures in relation to TSE cases. Whenever TSE is suspected in a holding, the competent authority must be notified and the holding must be put under official control including moving restrictions until the final testing results are available. If TSE is confirmed, the entire body of the animal concerned must be disposed of by incineration. An inquiry to identify all animals at risk of having TSE must be carried out. For BSE, all animals at risk must be culled and disposed of as well as the products derived from them. See Annex VII to the TSE Regulation.
Placing on the market, export and import
Rules on trade are laid down for live animals, their semen, embryos and ova as well as products of animal origin. See Annexes VIII and IX to the TSE Regulation. See the topic Impact on trade.
The feed ban is the basic preventive measure laid down against TSE and consists of a ban on the use of processed animal protein (PAP) in feed for farmed animals. Findings by the scientific committees linked the spread of BSE to the consumption of feed contaminated by the infected ruminant protein in the form of PAP. In other words, PAP produced from ruminant carcasses, some of which were infected, was assumed to be the transmission route of BSE. Based on these findings a ban on the feeding of mammalian processed animal protein to cattle, sheep and goats was introduced in July 1994. The ban was expanded in January 2001 with the feeding of all processed animal proteins to all farmed animals being prohibited, with certain limited exceptions. This is to ensure that there is no cross-contamination between feed containing PAP intended for species other than ruminants and feed intended for ruminants. Only certain animal proteins considered to be safe (such as fishmeal) can be used, and even then under very strict conditions.
The existing derogations provided for in Annex IV to the TSE Regulation are summarised here. They are based on strict channelling requirements (to avoid the cross-contamination, in particular between materials for which derogation to the feed ban is provided for feed intended to non-ruminant animals only, and feed intended to ruminants, and between prohibited ruminant materials and feed for farmed animals).
Official controls must be carried out by the Member States' competent authority to verify the correct application of the feed ban, based on laboratory analytical methods, as laid down in Annex I and Annex VI to Regulation (EC) No 152/2009. The validation of analytical methods for the official controls of the feed ban is carried out by the EU Reference Laboratory (EURL) for Animal Proteins in Feedingstuffs, which also organises interlaboratory studies to ensure the excellence of performance of National Reference Laboratories (NRL).
The EU feed ban provisions are reviewed regularly based on EFSA opinions and the development of new analytical methods for official controls. As regards scrapie, Annexes VII to the TSE Regulation bans the use as feed of milk and milk products coming from classical scrapie infected flocks for feeding ruminants.
Adequate surveillance forms the basis for other TSE control and eradication measures as it allows to have a reliable knowledge of the epidemiological situation. Since May 1998, EU-wide measures on surveillance have been in place. Each Member State has to carry out an annual monitoring programme for TSEs based on active surveillance (testing without previous suspicion) and passive surveillance (testing of clinical suspects identified by veterinarians/farmers) which applies to both bovine animals and ovine and caprine animals. The monitoring programme provides a reliable insight into the prevalence and evolution of TSEs in the Member States and at the same time ensures that no BSE cases are being slaughtered for human consumption. See Annexes III and X to the TSE Regulation.
BSE-monitoring of bovine animals
The active surveillance covers testing of two categories of bovine animals:
- The testing of all "at risk" animals over 24 months of age, which either are not slaughtered for human consumption, such as fallen stock which have died or been killed, but not in the framework of an epidemic, or are emergency slaughtered animals or animals with clinical observations at the ante mortem inspection preceding slaughter.
However, based on a favourable epidemiological situation most Member States have been authorised to apply a revised annual BSE monitoring programme and test only risk animals over 48 months of age provided that the animals have been born in those Member States. The list of Member States authorised to apply a revised annual BSE monitoring programme is laid down in Commission Decision 2009/719/EC.
- The testing of all healthy slaughtered animals over 30 months of age. However, the Member States which are authorised to apply a revised annual BSE monitoring programme according to Decision 2009/719/EC are allowed to no longer test healthy slaughtered bovine animals.
The passive surveillance consists of testing animals identified as BSE suspects by the veterinarian or the farmer.
TSE monitoring of ovine and caprine animals
The active surveillance covers testing of three categories of sheep and goats:
- Animals over 18 months of age which are not slaughtered for human consumption, such as fallen stock, which have died or been killed, but not in the framework of an epidemic. There are minimum sample sizes for both ovine and caprine animals.
- Animals culled in the framework of TSE eradication and animals from infected herds where the culling measures have been delayed.
- Healthy animals over 18 months of age slaughtered for human consumption. Only Member States with major ovine or caprine populations are required to test an annual minimum sample size of such animals.
The passive surveillance consists of testing animals identified as TSE suspects by the veterinarian or the farmer. See Annex III to the TSE Regulation.
TSE monitoring in other animal species
A survey for chronic wasting disease (CWD) in cervids was carried out during 2006-2008. See Commission Decision 2007/182/EC. No positive cases were found at the time.
The TSE Regulation includes a provision requiring the examination of TSE suspicions in all animal species, including cervids. Active monitoring in species other than bovine, ovine, caprine and cervid animals is voluntary and without further specifications. In case of detection of a positive TSE case, the animal must be culled and destroyed by incineration.
Report and Studies
- Annual reports of Member States on the monitoring and testing of ruminants for the presence of transmissible spongiform encephalopathies (TSEs) in the EU provide an overview of the monitoring results and epidemiology of TSEs, which assists the development of policy for the protection of human and animal health.
Only post mortem diagnostic tests are able to detect TSE, i.e. it is currently impossible to diagnose whether a live animal (or human being) is infected by a TSE.
The national reference laboratories (NRLs) and the EU Reference Laboratory (EURL) for TSE and their duties and tasks are listed and the rules for sampling and laboratory testing including approved rapid tests are laid down in Annex X to the TSE Regulation. The EURL for example carries out regular interlaboratory studies assessing the performance of the NRLs and ensures that the harmonised diagnostic techniques are used throughout the EU.
The commonly accepted cause of TSE is a misshaped prion protein (PrPres). This misshaped protein induces normal proteins to become equally misshaped. These proteins clump together to form sheets. There are other theories of the cause of TSE and some variations of the above theory. The presence of PrPres is regarded as a marker for the disease. TSE tests will determine if detectable levels of PrPres (either the cause of TSE or a marker for the disease) is present in the central nervous system. Following the slaughter or death of an animal, a sample of the brain or spinal cord is taken from the animal using a special tool and tested in a laboratory for the presence of PrPres. Rapid tests are quick, reliable and allow large numbers of samples to be tested.Samples collected in active TSE surveillance are screened by an approved rapid test. In inconclusive or positive cases the sample shall be submitted to a confirmatory examination by histopathology, immunohistochemistry, immunoblotting, demonstration of characteristic fibrils by electron microscopy, in the case of bovine animals, by a different rapid test, and in the case of small ruminants, by a mouse bio-assay method. Further discrimination between BSE and scrapie in TSE-positive ovine and caprine animals is mandatory, except in cases which are confirmed to be atypical scrapie. In case of confirmed positive case of BSE in a bovine animal, further discriminatory tests are mandatory to determine if the BSE case is Atypical (H-type BSE or L-type BSE) or Classical.
Precise rules for the diagnostic tests and diagnostic methods required to be applied are laid down in Annex X to the TSE Regulation.
Sampling and testing for the prion protein genotype
All TSE positive ovine animals are genotyped and in addition, a minimum representative sample of the ovine population must be genotyped each year to assess the frequency of each genotype. The alleles are defined by reference to the amino acids encoded by codons 136, 141, 154 and 171 of the prion protein gene, since these codons have been identified as relevant for determining the susceptibility or resistance of sheep to TSEs. Routine methods for the collection of samples and DNA genotyping are used.
Specified Risk Materials
Specified Risk Materials (SRM) are the tissues of bovine, ovine and caprine animals where BSE infectivity is most likely to occur. SRM must be removed from the food and feed chain and destroyed. For bovine animals, the list of SRM depends on the BSE status of the country of origin of the animal slaughter. The list of SRM currently in force, in accordance with Annex V to the TSE Regulation, is summarised here.
Since the adoption on 6 May 2015 of Commission Regulation (EU) 2015/728 amending Annex V to the TSE Regulation, for the intestines of bovine animals originating from countries with controlled or undetermined BSE risk, only the last four meter of the small intestine, the caecum and the mesentery must be considered as SRM and removed, instead of previously the entire intestine from the duodenum to the rectum and the mesentery.
5 short videos and a report are available below to help operators to implement in practice this revised requirement:
- Video part 1: bovine anatomy
- Video part 2: oral BSE uptake
- Video part 3: slaughter line
- Video part 4: removal of the last 4 meters of the small intestine
- Video part 5: removal of the ceacum
Disclaimer: The content of the above videos and report does not reflect the official opinion of the European Commission. Responsibility for the information and views expressed in the videos and report lies entirely with the author(s).
Annex V to the TSE Regulation also contains a prohibition for all Member States to produce mechanically separated meat from bones of bovine, ovine and caprine animals, as well as a prohibition for all Member States to use a technique called "pithing" (the laceration of central nervous tissue by means of an elongated rod-shaped instrument introduced into the cranial cavity after stunning, or by means of gas injection) when slaughtering bovine, ovine or caprine animals.
Inspection, Controls and Import Requirements
Member States are responsible for ensuring that EU legislation is properly enforced in their respective territories. The Directorate General for Health and Food Safety of the European Commission (DG SANTE) carries out audits in the Member States to verify the correct implementation, enforcement and control of EU legislation by the competent national authorities. DG SANTE audits also non-EU countries exporting or wishing to export animals or animal products to the EU. See DG SANTE's audit reports.
Under EU legislation, imported products must meet the same safety standards as products produced in Member States. Therefore, strict import requirements related to TSEs are laid down in Annex IX to the TSE Regulation, such as full traceability of imported animals and the animal products, a ban on the use of meat-and-bone-meal (MBM) in feed for ruminants, no prohibited ingredients such as specified risk material (SRM) or mechanically recovered meat, must have been used in the imported animal products, and the imported animals must not be cohorts of BSE-cases.The detailed import requirements depend on the BSE status of third countries or regions thereof, as laid down in Commission Decision 2007/453/EC.
Until May 2003, the scientific opinions were provided by the Scientific Steering Committee.
Since May 2003, the scientific opinions are provided by the European Food Safety Authority (EFSA). EU measures on TSEs are based on sound, independent and transparent scientific advice and opinions from leading experts. In EFSA, Opinions on TSEs are adopted by the BIOHAZ Panel (biological hazards). Further information and all Scientific Opinions on TSEs adopted by EFSA can be found on the EFSA website.
The Commission has sponsored research into TSEs since 1990 under several framework programmes. The Seventh Framework Programme for research and technological development (FP7) for the years 2007-2013 is the European Union’s main instrument for funding research into TSE. Please refer to DG Research and Innovation for more information on research in general and to this page for more information on FP7.