One of the most worrying consequences of the outbreak of the Great Britain of the "mad cow" - that humans could be infected by the contaminated beef-- consumption? seems to be confirmed by the research to be published this week in Nature .
More than 20 Britons have died in recent months from what is called variant Creutzfeldt-Jakob disease (vCJD). The symptoms are similar to those of classical CJD, a fatal brain disease that progresses slowly. But vCJD tends to strike young people, and it is growing much faster. A link between vCJD and mad cow disease, bovine spongiform encephalopathy (BSE) was suspected, because both involve dementia, tremors, and this can be an infectious protein called a prion. But the evidence ( Science NOW, October 23, 1996) that the consumption of beef contaminated with BSE may cause vCJD was inconclusive.
In the new work, Moira Bruce of the Institute for Animal Health in Edinburgh, Scotland, and colleagues injected mice with infectious brain samples of cattle with BSE, patients died of vCJD, and patients with classic CJD. After considering how and where the mouse brains were damaged, and the symptoms and progression of the disease, the researchers concluded that vCJD and BSE in mice are the same, and the two are distinct from classical CJD.
A team from the Imperial College School of Medicine in London, led by John Collinge, adds further evidence to the puzzle in Nature separate. Collinge and colleagues demonstrate biochemically that the infectious agent responsible for BSE can turn normal human infectious prions in mice. The "inevitable conclusion" said Collinge, is that the new vCJD is the human equivalent of BSE and the consumption of infected beef is probably to blame.
A key question now is how many people may have been infected, but researchers still have no answers. "It may take several years before we can be sure that this is not a period of relative calm before the storm," says Jeffrey Almond at Reading University and John Pattison at University College London. "It all depends the average incubation period of vCJD, and, at present, we can not calculate. "
0 Komentar