For the first time, a tissue sample removed in Britain during routine surgery has tested positive for the human form of bovine spongiform encephalopathy (BSE). The find has reopened the debate over whether people found to be incubating the fatal neurodegenerative disease should be informed.
Last week, researchers announced that they had turned up one positive sample of the misshapen protein, or prion, thought to cause variant Creutzfeldt–Jakob disease (vCJD), among 8,318 tonsils and appendices removed from patients in the late 1990s (D. A. Hilton et al. Br. Med. J. 325, 633–634; 2002). Earlier data from 3,000 samples had returned negative results (see Nature 405, 7; 200010.1038/35011219).
From this, the researchers estimate that about 120 out of every million Britons might eventually develop vCJD, thought to be the result of eating meat products from cattle infected with BSE. That number falls within previous estimates, based on epidemiological modelling, of several thousand cases. But, given that the new calculations are based on just one case, the margin of error remains large. “We're not going to jump to any conclusions,” says David Hilton of the Derriford Hospital in Plymouth, who led the team.
Hilton says that testing of further samples under the existing study, in collaboration with the CJD Surveillance Centre in Edinburgh, will continue through next year. And the British government's chief medical officer, Liam Donaldson, adds that a larger tissue-screening study is planned, which may further clarify the disease's eventual prevalence.
Meanwhile, Swiss scientists have begun their own screen of tissues from surgery and autopsies. Adriano Aguzzi, a neuropathologist at the University Hospital in Zurich, says doctors will examine thousands of samples over the next decade or so. But whereas the UK survey is anonymous, so that patients who test positive cannot be notified, the Swiss survey will retain patients' details.
“We think the science in the prion field is advancing very quickly, and it's not unlikely that in three or five years' time there will be a way to block the prion from causing disease,” says Aguzzi. If therapy becomes available, Swiss test results will be made available; they will also be disclosed to specific patients who request them even in the absence of a cure.
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Notification and support for people exposed to the risk of Creutzfeldt-Jakob disease (CJD) (or other prion diseases) through medical treatment (iatrogenically)
Cochrane Database of Systematic Reviews (2011)