Q. What is the public health risk associated with the discovery of a case of classical BSE in Scotland?
There are strict controls in place to protect consumers from the risk of BSE, including controls on animal feed, and removal of the parts of cattle most likely to carry BSE infectivity.
Consumers can be reassured that these important protection measures remain in place and that Food Standards Scotland Official Veterinarians and Meat Hygiene Inspectors in All Scottish slaughterhouses will continue to work to ensure that in respect of BSE controls, the safety of consumers remains a priority.
Q. What is Bovine Spongiform Encephalopathy?
Bovine Spongiform Encephalopathy (BSE) is a disease in cattle. It belongs to a group of diseases called Transmissible Spongiform Encephalopathies (TSEs) that affect the brain and nervous system of humans and animals. The diseases are characterised by a degeneration of brain tissue giving it a sponge-like appearance
Q. What is Classical BSE?
Epidemic classical BSE occurs through the consumption of contaminated feed. Whilst classical BSE was identified as a significant problem in the 1990s, its occurrence has markedly decreased over the past years, as a result of the successful implementation of effective control measures.
Q. When was the last confirmed case of Classical BSE in Scotland?
October 2018, from an animal born in 2013. The case was detected during routine surveillance of fallen stock cattle. The animal was not presented for slaughter and did not enter the food chain. The last case prior to then was in 2008, from an animal born in 1994.
Q. What is the current situation in Scotland?
A case of classical BSE has been confirmed in a pedigree beef cow in Aberdeenshire. Further information on this case can be found below.
Prior to the most recent BSE case, Scotland had been BSE free since 2009. In the years before that, there were relatively low numbers of BSE cases compared to the peak of the epidemic when there were 2208 clinical cases in the 1993 . The marked decrease in the number of cases detected through passive surveillance is consistent with the long tail previously predicted by epidemiologists.
Q. When will we know the cause of the outbreak?
The Animal Health Agency (APHA) is investigating the source of the outbreak and will update in due course.
Q. Does a confirmed Classical case of BSE affect Scotland’s negligible risk BSE status?
Yes, a confirmed case of classical BSE will alter Scotland’s BSE status to Controlled Risk. Scotland will now have the same status as England and Wales.
Q. What is Scotland doing to monitor BSE?
An active BSE surveillance programme has been in place since 2001 and is carried out on all fallen livestock that die on farm over 48 months old by approved facilities. Scotland takes BSE samples from over 20,000 fallen cattle each year.
Q. Can humans get BSE?
A. An extremely rare form of spongiform encephalopathy called variant(v) Creutzfeld-Jakob Disease (CJD) occurs in humans and is likely to be caused by consuming meat from a cow that has been infected with BSE, a similar prion disease to vCJD. Since the link between vCJD and BSE was discovered in 1996, strict controls have proved very effective in preventing meat from infected cattle entering the food chain.
Q. What are signs of BSE in cattle?
Cattle affected by BSE experience progressive degeneration of the nervous system. Affected animals may display changes in temperament (nervousness or aggression), abnormal posture, incoordination and difficulty in rising, decreased milk production, or loss of condition without noticeable loss of appetite. The causative agent of the disease is not completely characterised, and there is neither any treatment nor a vaccine to prevent the disease. The incubation period is from 2 to 8 years. Following the onset of clinical signs, the animal's condition deteriorates. This process usually takes from 2 weeks to 6 months. Any farmer with concerns should immediately seek veterinary advice.
Q. How is BSE actually spread?
The disease is not contagious so it does not spread. Scientific opinion based on the known evidence is that it can be transmitted by infected feed, and a ban on feeding any animal protein to ruminants was put in place in 1996.
The following controls are currently in force in the UK:
- The feed ban applies to all ruminants and all non-ruminant farmed species.
- Under the feed ban it is illegal to feed (with certain exceptions e.g. milk and eggs) animal protein to ruminants and it is illegal to feed (with certain exceptions) processed animal protein to farmed animals.
Q. How did BSE emerge?
There are different scientific hypotheses concerning the origins of BSE. The disease may have been caused by feeding cattle rendered protein produced from the carcasses of cattle with a previously unidentified transmissible spongiform encephalopathy (TSE). That was the preferred conclusion of the BSE Phillips Enquiry into its origins.
Q. What is the agent that causes BSE?
Research suggests that a pathogenic form of a normally occurring protein known as a prion (PrP.) is the cause.
The pathogenic form of the prion protein (PrPSc) is extremely resistant to heat and to normal sterilization processes, making it difficult to inactivate with standard methods used to process human food and animal feed. Although rendering and other processes can partially inactivate PrPSc, the risk mitigation strategies (for meat and meat products) rely mainly on the elimination of tissues and organs known to harbour BSE infectivity in infected animals, which are known as specified risk material (SRM).
Q. What is specified risk material (SRM)?
A. Specified risk material (SRM) is those parts of cattle, sheep and goats that are most likely to pose a risk of infectivity if the animal which it comes from was infected with a transmissible spongiform encephalopathy (TSE) prion. It is essential, therefore, that it is removed from both the human and animal food chains and destroyed.
Q. What is a prion?
Prions are the only agent without nucleic acids (DNA and RNA) that are capable of infecting a living host and reproducing themselves once inside. Proteins similar to prions already exist in the nervous tissue cell membrane in healthy animals, but in a harmless form. After an incubation period of many years, prions in an infected host reproduce by recruiting the host's similar, harmless protein and changing its shape to that of the prion. Some individuals appear to be genetically susceptible to prion diseases.
Q. Are there any known tests to detect the disease in cattle?
Currently, there is no test to detect the disease in a live animal. BSE is confirmed by either histopathological examination of brain tissue or by the detection of the abnormal form of the prion protein via one of several methods, also requiring brain tissue.
Q. Is cow's milk and milk products a source of TSE?
No. Scientific research indicates that TSEs cannot be transmitted via milk or milk products, even if the milk comes from a TSE-infected animal.
Confirmed Classical BSE case in Aberdeenshire (as of 5 November 2018)
A case of Classical BSE has been confirmed in a cow from a pedigree farm in Aberdeenshire, Scotland on 18 October 2018. A Scottish Government press release can be found here.
The farm operates as a closed herd and cattle are grass fed.
The animal had been showing signs of illness and a private veterinary practitioner diagnosed and treated her for hypomagnesaemia (grass staggers) several days before she died.
The animal was sampled for BSE as per surveillance requirements to test all cattle over 48 months old that die on farm. Initial test results could not rule out the animal being positive for BSE and further confirmatory testing was carried out.
The Animal and Plant Health Agency (APHA) were notified according to standard protocol and movement restrictions were placed on the farm since BSE was first suspected. The movement restrictions have now been lifted.
Preliminary investigations by APHA have identified 3 cohorts and 1 offspring. Cohorts are animals born in the same herd which have been potentially exposed to the same feed. No cohorts have left the farm.
The cohort and offspring animals have been humanely destroyed and tested negative for BSE.
Food Standards Scotland and Health Protection Scotland are aware and state there is no change to risks to human health because appropriate controls are, and already were in place.
APHA will carry out a further detailed epidemiological investigation on the farm to establish, if possible, the source of the disease.