Mad Cow Disease Dying Out Worldwide
ROME, Italy, March 28, 2006 (ENS) - Cases of mad cow disease worldwide are fewer year by year, according to two international agencies that specialize in surveillance of animal health. Cases of the fatal brain-wasting disease formally known as bovine spongiform encepalopathy (BSE), have been declining at the rate of some 50 percent a year over the past three years.
In 2005, just 474 animals died of BSE around the world, compared with 878 in 2004 the UN Food and Agriculture Organization (FAO) said Thursday. The agency relies on figures collected by the Paris-based World Animal Health Organization (OIE).
OIE figures also show that 1,646 animals died of the disease in 2003, as compared with a peak of several tens of thousands in 1992.
Andrew Speedy, an FAO animal production expert, said, ìIt is quite clear that BSE is declining and that the measures introduced to stop the disease are effective. But further success depends on our continuing to apply those measures worldwide.î
Only five human deaths resulting from variant Creutzfeldt-Jakob Disease (vCJD), the human form of BSE, were reported worldwide in 2005. All of them were in the United Kingdom ñ the country most affected by the disease ñ where nine vCJD deaths were registered in 2004 and 18 in 2003.
According to the World Health Organization, vCJD is a new disease that was first described in March 1996.
The latest report from the UK Department of Health, issued on March 3, 2006, shows 110 confirmed deaths from definite vCJD.
There have been 44 deaths from probable vCJD, without neuropathological confirmation. Six people who are considered probable vCJD cases are still alive.
Cattle can become infected with BSE by consuming feed that contains brain and spinal cord tissue of infected animals. A ban on feeding mammalian protein to cattle has been in effect since 1996 in the UK, and since 1997 in many other countries.
BSE is a transmissible, neurodegenerative, fatal brain disease of cattle. The disease has a long incubation period of four to five years, but ultimately is fatal for cattle.
BSE first came to the attention of the scientific community in November 1986 with the appearance in cattle of a newly-recognized form of neurological disease in the United Kingdom.
Since then, a total of 181,376 cases of BSE have been reported in the UK.
The number of reports of BSE in the UK began to fall in 1992 and has continuously declined year by year since then.
In 2002, only 755 cases were reported in the UK; but there were 891 from the 21 other countries reporting BSE cases.
Since 1989, when the first BSE case was reported outside the UK, 3,286 cases in total have also been reported in native cattle in other countries - Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Israel, Italy, Japan, Liechtenstein, Luxembourg, Netherlands, Poland, Portugal, Slovakia, Spain, Switzerland and the United States.
All but 206 cases have been reported in six countries outside the UK - France, Germany, Ireland, Portugal, Spain and Switzerland.
Studies conducted in the UK suggest that the source of BSE was cattle feed prepared from bovine tissues, such as brain and spinal cord, that was contaminated by the infective agent.
The nature of the BSE agent is still a matter of debate, the World Health Organization says. According to the prion theory, the agent is composed of a self-replicating protein, referred to as a prion.
Another theory argues that the agent is virus-like and possesses nucleic acids which carry genetic information.
Strong evidence collected over the past decade supports the prion theory, but the ability of the BSE agent to form multiple strains is more easily explained by a virus-like agent, says the World Health Organization.
The FAO insists on the importance of a scientific approach to detect and control the disease, ensuring it is eradicated in affected countries and kept out of countries where it has never appeared.
The FAO, together with Swiss experts, has been running courses for specialists from countries as far afield as Serbia, Egypt, Vietnam, Argentina, Brazil, Chile, Colombia, Mexico, Peru, Uruguay and Paraguay on BSE diagnosis, surveillance and prevention in the animal feed and meat industries.
Speedy says a tracking system that allows animals to be identified "from birth to shopping basket" is vital for controlling BSE. Animal tracking systems have been adopted across Europe but have yet to be implemented partially or fully in a number of other countries, including the United States.
The decline in worldwide cases of mad cow disease was predicted in 1997 by mathematical epidemiologists Neil Ferguson, Roy Anderson and colleagues at Oxford University, who said their models showed earlier predictions that the epidemic would be largely over by 2005 were correct.
