Questions and answers about BSE
What is BSE?
Bovine Spongiform Encephalopathy (BSE) is a disease that affects adult cattle. BSE attacks the brain and central nervous system of the animal and eventually causes death.
Commonly known as 'Mad-Cow Disease', BSE has a long incubation period. This means that it usually takes four to six years for cattle infected with BSE to show signs of the disease, such as disorientation, clumsiness and, occasionally, aggressive behaviour towards other animals and humans.
Where does BSE come from?
BSE was first confirmed in cattle in the UK in 1986. The first case in Ireland was confirmed in 1989, when there were 15 cases confirmed. Most experts agree that BSE was most likely spread by cattle eating feed that contained contaminated Meat and Bone Meal (MBM). MBM is produced in a process called rendering. This is where otherwise unused animal products are taken from the carcass and are cooked for a long time to produce MBM. MBM was incorporated into cattle feed until it was banned in the 1990s.
Experiments have shown that cattle can contract BSE if they are fed infected brain tissue. This supports the idea that BSE was transmitted to cattle through their animal feed.
The practice of feeding MBM to cattle has been banned in Ireland since in 1990. Controls on MBM were strengthened in 1996 -1997. Due to the BSE crisis in other Member States, a ban was introduced throughout the EU on feeding MBM to all farm animals in 2001.
What danger is BSE to people?
BSE only develops in cattle, but it belongs to a family of prion diseases, several of which can affect humans. The most commonly known disease in this group among humans is Creutzfeldt-Jakob Disease (CJD). This is a rare and fatal form of dementia that normally occurs in individuals between the ages of 40 and 80.
CJD is not a new disease among humans, but in 1996, scientists discovered a new strain of CJD that occurs predominantly in younger people. The protein that accumulates in the brains of individuals with this new form of CJD is similar to the protein found in cattle infected with BSE, rather than that found in classical CJD. The new illness in humans is therefore known as variant CJD or vCJD.
The occurrence of this form of CJD in the UK, where there was a high incidence of BSE, suggested that there might be a direct link between BSE and vCJD. Some individuals who have developed vCJD are known to have eaten potentially BSE-infected meat products. Researchers concluded that the most likely origin of this new disease was human exposure to the BSE agent. Like BSE in cattle, vCJD is always fatal in people.
Where an animal has BSE the prion will be concentrated in a limited number of tissues such as the brain and spinal cord. These tissues are defined as Specified Risk Materials (SRM). SRM from all cattle are systematically removed from the food chain and are disposed of by rendering, followed by incineration. Removal and destruction of SRM is the principal public health/food safety control.
How is BSE being controlled in Ireland?
BSE controls in place in Ireland since 1996 are very strict and there are layers of robust measures to ensure maximum consumer protection in relation to BSE.
The Food Safety Authority of Ireland (FSAI) bases its decisions upon the best scientific data and knowledge, and develops inspection and audit controls to ensure maximum consumer protection in relation to meat and meat products.
The following risk reduction measures are in place in Ireland :
- The Cattle Movement Monitoring System (CMMS) which tracks the location of all animals in the national herd.
- Ante-mortem examination, by a veterinary inspector, of all animals prior to slaughter at all abattoirs and verification of each animal's status via the CMMS, ensures that only healthy animals are slaughtered for human consumption.
- Detailed post-mortem examination of all beef carcasses and offals.
- The screening of all suspect cattle using an approved test.
- Removal of all Specified Risk Material (SRM) at the abattoir.
- Extensive checks by veterinary inspectors to ensure that the removal of SRM has been thoroughly carried out.
- On-going audit by FSAI of the effectiveness of controls at abattoirs and meat retail outlets.
- The separation, staining, and separate storage and processing of all SRM to ensure its total exclusion from the human and animal food and feed chains.
- The processing of all SRM in a high temperature, high-pressure process at designated facilities, supervised by the Department of Agriculture, Food and the Marine.
- The exclusion of all meat and bone meal products from the animal feed chain.
What is Specified Risk Material (SRM)?
SRM are the parts of cattle most likely to carry the BSE prion and these are systematically removed from the carcase at the abattoir. These parts are:
- The skull excluding the mandible and including the brain, eyes and the spinal cord of animals aged over 12 months
- The tonsils, the last four metres of the small intestine, the caecum and the mesentery of animals of all ages
- The vertebral column excluding the vertebrae of the tail, the spinous and tranverse processes of the cervical, thoracic and lumbar vertebrae and the median sacral crest and wings of the sacrum, but including the dorsal root ganglia, of animals aged over 30 months.