Recent cases of "mad cow disease" are isolated incidents
Three cases detected in Canada and one in the US
7 February 2005, Rome --The few cases of Bovine Spongiform Encephalopathy (BSE) or 'mad cow disease' in cattle in Canada and the US should not cause panic among consumers and producers, the UN Food and Agriculture Organization (FAO) said in a statement today. Nor should the single case of BSE recently confirmed in a goat in France.
"The three cases in Canada and the one case in the US from an imported animal are isolated incidents," said Andrew Speedy, an FAO animal production expert. These cases were detected because of the testing procedures that are now in place. More than 176 000 tests out of a total cattle population of almost 95 million have been carried out in the USA and more than 21 000 out of 14.5 million cattle in Canada during 2004. A ban on feeding ruminant protein to ruminants has been in place in both countries since 1997.
Western European countries experienced significant numbers of BSE cases in 2001-2002 but the disease is declining now in the region. There have also been some cases in Eastern Europe, Israel and Japan.
FAO said there is a need for a steady, scientific approach to ensure that the disease is kept out of unaffected countries. Identification of animals by the use of ear tags or electronic systems, national registration and movement records, compulsory testing of suspect animals, and general awareness, especially among producers and their veterinarians, are all part of essential control measures. Incentives may need to be given to encourage detection of suspect cases.
"There is still some lack of understanding about BSE and how it can be detected and controlled," Speedy said. BSE can only be identified in adult animals; the animals that must be tested are cows that are casualties and fallen stock. "There is no point in testing all animals in slaughterhouses, because most of them are too young to detect the disease," Speedy said. "It should be remembered that symptoms can vary and affected cattle may not appear really 'mad'."
FAO is working with Swiss experts to train people/veterinary staff in other countries, including Asia, Eastern Europe, Latin America and the Near East, in methods of diagnosis, surveillance and prevention.
"Switzerland had its first case of BSE in 1990 and peaked at 68 cases in 1995", pointed out Speedy. "There were just 3 cases in 2004, demonstrating how effectively the system has worked in Switzerland."
Switzerland has a fool-proof system of cattle identification and registration, a scientific testing programme, preventative measures in the rendering and animal feed industry and complete support throughout the food chain.
BSE is a fatal disease of adult cattle characterized by degeneration of the central nervous system. The causative agent is thought to an abnormal form of a protein called a 'prion'. BSE was first diagnosed in cattle in the United Kingdom in 1986. The transmission of BSE is thought to be by the oral ingestion of animal feed containing BSE-infected meat and bone meal (MBM).
The goat diagnosed with BSE in France was the first food animal other than cattle to contract the disease naturally. It was thought that sheep and goats were only affected by scrapie which is distinguishable from BSE and not thought to be transmissible to humans. But FAO stressed that this is one example in millions, and the goat was born before Europe imposed a total ban on feeding of MBM to livestock in January 2001.
Scientists believe that BSE causes variant Creutzfeldt-Jakob Disease (vCJD) in humans, by consumption of contaminated beef products from infected cattle. The particular variant form of the human disease has caused 148 deaths in the last 10 years, almost all in the UK. The recent case in Japan was a person who had visited the UK.
Essential control measures include the exclusion of potentially infective materials (Specified Risk Materials or SRMs) from the food and feed chain and improved practices in the rendering and feed industries. "It is not sufficient just to ban meat and bone meal from ruminant feeds," Speedy said.
"Cross contamination can occur in the feed mills, as well as during transport and on the farm. It was shown in Switzerland that a total ban on MBM was necessary to prevent transmission of infective material." Alternatively, pig and poultry lines must be kept entirely separate in feed mills. FAO urges countries to apply the same safety measures.
Research is finding out more about the disease and its epidemiology but vCJD remains a rare disease in humans and BSE is declining in the animal population.
Information Officer, FAO
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