North American and German researchers announced a breakthrough Friday toward a cheap, fast blood test for BSE or mad cow disease in livestock.
The research paves the way for a simple blood test "to eliminate infected animals from the human food chain, even before the onset of clinical signs," said the report, published this month in the Nucleic Acids Research journal.
AdvertisementEating meat from animals infected with BSE (bovine spongiform encephalopathy) has been linked with a new form of the fatal, brain-wasting Creutzfeldt-Jakob disease, which has killed at least 200 people worldwide.
Currently the only way to accurately test for BSE, and for similar wasting diseases that affect sheep, elk and other relatives of cattle, is to dissect each animal's brain after slaughter, said principal investigator Christoph Sensen of the University of Calgary.
More tests are needed, Sensen told AFP in a telephone interview, but he predicted that within a few years slaughterhouses will conduct routine tests on all animals to rule out the disease.
Each two-dollar test could potentially cover 10 animals and take about two hours, he said.
"It's a fairly simple thing ... it could be done by veterinarians in slaughterhouses as animals go in, as part of the pipeline that processes beef.
It's a very promising breakthrough because it tests blood instead of brains, and live animals instead of dead animals," he said.
The scientists infected elk and cattle by feeding them several grams of infected brain material. The rate of both infection and fatality was 100 per cent, noted Sensen. "It's very dangerous, deadly stuff," he said.
As the elk infected with Chronic Wasting Disease took about two years to sicken and die, scientists drew blood from each animal monthly and tested circulating nucleic acids, said Sensen.
Months before the infected animals showed the first visible symptoms of disease, he said, scientists detected patterns in the blood, genetic material unique to diseased animals, and not found in healthy animals.
The genetic changes were caused by the creature's responses at a molecular level to the stress of the infection.
"We are measuring what genes are being turned on, and when," said.
Full testing of the cattle infected with BSE will take longer than tests on elk, partly because cattle take longer to die, said Sensen, adding that the researchers are also developing tests for bison, sheep and other species.
In the future, said Sensen, the livestock tests may help doctors diagnose Creutzfeldt-Jakob disease in humans, adding that it could "also be used in other chronic diseases, like Alzheimer's and Parkinson's."
The research team included scientists from the University of Calgary, Alberta and Canadian government agencies, Germany's Federal Research Institute for Animal Health and the University of Goettingen, and Chronix Biomedical of the United States.
Wasting diseases are an economic as well as a human health threat.
Infections have been periodically detected in cattle throughout much of Europe and North America, leading to global import bans from affected countries and mass slaughters, including about 4.4 million animals killed during a 1990's outbreak in Britain.
The human variant of the disease, first described in 1996, was found to be triggered by eating meat from infected animals, and in a bid to prevent more cases the European Union has banned high-risk materials such as spinal cord from use in feed.