Agence France Presse | By RICHARD INGHAM | May 20, 2003
As few as 40 people may die over the next eight decades from eating meat infected with mad-cow disease, according to a study published Tuesday which boosts hopes that after seven years and an astronomical bill, the scare has finally peaked.
The estimate by researchers at Imperial College London is based on the latest data from the epidemic of variant Creutzfeldt-Jakob disease (vCJD), which is overwhelmingly centered in Britain, the source of mad-cow disease.
In 2000, epidemiologists triggered alarm when they admitted they had so little knowledge about vCJD that its final death toll, over the next 40 years, ranged from a few score to up 136,000.
But the data flow has improved considerably since then, and the mortality estimates have plunged over the past two years.
The Imperial College team looked at people who carry a specific genetic variation that appears to make them more susceptible to vCJD than others; around 40 percent of Britain's Caucasian population have this genotype.
They also calculated the number of Britons who had eaten infected meat before tough new laws in the mid-1990s choked off that supply.
They did not include other ways of catching the disease, such as through contaminated surgical instruments or blood transfusions, or explore the possibility that other genetic types could be at risk.
"Our results show a substantial decrease in the uncertainty in the future course of the primary epidemic in the susceptible genotype... (it) appears to be in decline," they wrote.
The new estimates range from a worst-case scenario of 540 deaths by 2080, to only 40.
The incurable, untreatable, fatal disorder -- a variant of the well-documented Creutzfeldt-Jakob disease (CJD) -- is caused by a rogue prion protein that runs amok in the brain, turning it "spongey" by destroying brain cells.
In 1996, the first evidence emerged to link vCJD with eating beef infected with an animal equivalent of the disease called bovine spongiform encephalopathy (BSE).
That unleashed panic among British consumers and countries which imported British beef. Billions of dollars were spent in cattle culls and subsidies for farmers in the desperate bid to restore faith in the market.
One of the biggest mysteries about vCJD has been the time the disease takes to incubate.
This above all has made it difficult to figure out how many people have been infected and in turn hampers the task of erecting a social and health safety net to help them.
Some scientists have feared the incubation could be as long as three decades, which if true would amount to a looming health disaster in Britain.
The study makes the first "meaningful" attempt at answering the question, suggesting the disease takes 12.6 years to develop before the first symptoms appear.
That puts it in the same ballpark as a related disease called kuru, which affected cannibals in Papua-New Guinea who had eaten infected brain tissue.
A total of 132 cases of vCJD have been recorded in Britain, seven of whom are still alive, according to the website of Britain's CJD Surveillance Unit.
France, which used to be a big importer of British cows and beef, has recorded six cases of vCJD.
Ireland has had one death from vCJD, involving a woman who had lived in Britain, and Italy has recorded one death. There has been one death in Canada and one diagnosed case in the United States, both involving Britons who had lived in the United Kingdom.
The study was led by Azra Ghani and included Roy Anderson and Christl Donnelly, who have both been in the news of late for their assessment of the SARS epidemic.
It is published by BioMed Central, an independent online publishing house (www.biomedcentral.com/1471-2334/3/4).Agence France Presse:
