Bovine spongiform encephalopathy (BSE) or ‘mad cow disease’ is a degenerative, fatal brain disease of cattle. Prions are believed to be the infective agents, which cause BSE. BSE is concentrated mainly in the animal's brain, spinal cord and certain organs such as the spleen.

BSE cases have been reported in the United Kingdom, Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Israel, Italy, Japan, Liechtenstein, Luxembourg, Netherlands, Poland, Portugal, Slovakia, Spain and Switzerland. In 2003, Canada reported two and the U.S. reported one BSE-positive cow. Small numbers of cases have also been reported in the Falkland Islands and Oman, but solely in animals imported from the UK. More than 95% of cases identified have developed in the United Kingdom, and other countries involved are considered to be low risk.

As no laboratory test to confirm BSE in a live animal currently exists, BSE is diagnosed by microscopic examination of brain and spinal cord tissue after the animal’s death. Special laboratory tests are used to confirm the presence of the abnormal prion protein in brain and spinal cord tissue.

BSE and vCJD: The Link

A disease similar to BSE, known as new variant Creutzfeldt-Jakob Disease (vCJD), a rare, degenerative, fatal brain disorder affects humans. It is believed to result after infectious prions enters the human brain, where it can remain dormant for up to 15 years. Once the prion is activated, the disease will run its course within 12 to 18 months and ultimately result in death. Symptoms include depression, coordination problems, memory loss and mood swings, pins and needles and pain in the limbs, bad headaches, cold extremities, pain in the feet, rashes and short-term memory loss. To date, most cases of vCJD have been observed in young adults (median age at death is 28 years).

vCJD is believed to be caused by eating the organs and tissues from cattle in which the BSE-causing prions are present (i.e. brain, spinal cord, spleen). However, the risk for acquiring vCJD from consumption of BSE-contaminated product is low. There are 2 reasons for this. Firstly, the "species barrier" provides substantial (but not complete) protection against development of vCJD. Secondly, the incubation period for BSE is very long: 4–5 years and during this period, cattle exposed to the BSE agent show no BSE symptoms and have no infectious material in their tissues. Therefore, meat and meat products from cattle slaughtered under 30 months of age, are considered safe to eat.

Stringent slaughtering and butchering practices, which remove high-risk tissues of the central nervous system, most notably the brain and spinal cord, can protect consumers even when BSE is established in a country.

Safety of bovine products

On the basis of current knowledge, scientists agree that some bovine products are safe, regardless of the BSE status within a given country:

Beef –

Meat and meat products from cattle slaughtered under 30 months of age are free of infectious material. No prions have been detected in the skeletal muscle tissues, from which most quality meat is derived. Meat derived from muscle tissue is therefore assessed as safe to eat. Experts advise against the consumption of brains, neck bones, beef cheeks, bone marrow and cuts of beef that are sold on the bone.

Ground / Minced meat –

Check with meat suppliers and restaurants which serve ground beef that only skeletal muscle (100% beef) is used. Many restaurants and meat suppliers have implemented a very strict policy to ensure only skeletal muscle tissue is used. 100% beef ground beef is safe to eat, but ground meat products from unknown sources may contain neural tissue and advice in these instances is to avoid.

Processed meats–

An improved mechanical process for removing residual meat from bones has been developed in recent years. This process, called Advanced Meat Recovery System (AMR or AMRS) does not involve crushing bones, and therefore decreases the likelihood of contamination of meat with infectious nervous tissue. A more old-fashioned method involving the use of wire brushes and other mechanical tools to recover meat scraps attached to bones and the vertebral column can pull out infectious nervous tissue and contaminate meat that is otherwise safe. Health experts recommend this method should no longer be used. Check labels, or with supplier/retailer or restaurant the source of raw ingredients and method used for processed meats, or if in doubt, advice is to avoid

Milk –

Scientific research indicates that BSE cannot be transmitted through cow's milk. No infectious prions have been detected in milk, including milk taken from a BSE-infected cow. Thus, milk and milk products, even in countries with a high incidence of BSE are considered safe.

Gelatin –

Not only is gelatin derived from cattle hides and skin, which are considered low risk tissues for BSE transmission, but the manufacturing process for gelatin involves intense processing, which further reduces any BSE risk for humans to negligible levels. Also, as a further precaution, gelatin manufacturers have been advised against using bones and hides from cattle with any neurological disease and the heads, spines, and spinal cords of cattle from BSE countries.

Worldwide, authorities have therefore continually attested to the safety of gelatin. It continues to maintain its 'Generally Recognised as Safe' status within the US. The Scientific Steering Committee of the Health and Consumer Protection Directorate-General in the European Commission states that with appropriate sourcing of raw materials and using appropriate production processes, the BSE risk level of gelatin is close to zero. Hence gelatin can be safely used in food products, pharmaceuticals, dietary supplements, cosmetics and other industrial applications.

Dietary supplements with bovine-derived ingredients –

The risk to human health from dietary supplements is extremely low. Firstly, dietary supplement manufacturers and distributors have been advised against using ingredients that come from cattle born, raised or slaughtered in any country known to have BSE or that has inadequate methods to detect and control it. Secondly, most countries have procedures in place to monitor dietary supplements and their ingredients when they enter the country. And thirdly, it is important to note that most ingredients used to produce dietary supplements come from cattle that are slaughtered when they are less than 30-months of age and, because of their age, present little risk of being BSE-positive.

Beef flavourings and essences-

Some beef flavourings and essences used in products such as stock, soups and sauces, although conferring beef flavour, do not contain any substances of bovine origin and are therefore safe for consumption.

Collagen –

Collagen prepared exclusively from hides and skins is safe for consumption.

Tallow-

Tallow used in cooking or as a flavoring agent or in cosmetics is considered to be a low risk for transmission of BSE. Not only have food and cosmetic manufacturers been advised to acquire tallow from sources that do not include cattle with BSE, but the rendering process used to make tallow removes the infective prions and the excessive heat and pressure required during processing further minimizes risk of infectivity prior to its use in food or cosmetics.

Food safety measures to prevent the spread of BSE / Containment

The United Nations Food and Agriculture Organization recommends six specific preventive steps for containment of BSE:

• Banning the feeding of meat-and-bone meal to farm animals, or at least to ruminants (cud-chewing animals such as cattle and sheep)

• Preventing cross-contamination in feed mills to keep cattle parts intended for poultry or hog feed from ending up in cattle feed

• Removing and destroying "specified risk materials" (SRMs—tissues such as the brain, spinal cord, and certain nerve bundles, which are most likely to carry the BSE agent in infected animals) from carcasses of cattle over 30 months old

• Ensuring safe practices in the rendering industry, ie, exposing material to 133˚C at 3 bar pressure for 20 minutes

• Using active surveillance for BSE and providing for accurate identification and tracing of animals throughout production, processing, and marketing

• Banning the use of mechanically removed meat

According to the FAO, with these control measures in place, especially the ban on using cattle remains in feed, and removal of SRMs, the risk of BSE infective material being present in the food chain is extremely low.

To help countries to implement stricter controls, FAO is carrying out training projects in several countries. This training project targets not only inspectors and laboratory personnel but also those involved in the feed and meat industries, so that they are trained in "good practices" which minimize the risks throughout the food chain.

Policy advice from the OIE (World Organization for Animal Health) on surveillance is that countries test 1 in 100,000 to 1 in 10,000 cattle over 30 months old, as well as cattle with possible BSE symptoms. If BSE is known to be present and control measures have not yet been strictly applied, a wider testing programme is called for - testing of all slaughter cattle over 30 months is a measure to enhance consumer confidence.

Further Information Links:

·         World Health Organization: www.who.int

·         US FDA: www.fda.gov

·         World Organization for Animal Health: www.oie.int

·         Australian Government Department of Health and Ageing: www.health.gov.au

·         US Center for Disease Control and Prevention: www.cdc.gov

·         USDA: www.usda.gov