Testing for vCJD
In 1997, I did a research project at the National CJD Research and Surveillance Unit at Edinburgh’s Western General Hospital, supervised by Robert Will and James Ironside, who co-authored the 1996 paper in the Lancet that proposed the existence of vCJD in the UK. The only reliable way to diagnose the disease was by post-mortem examination of the brain, which would reveal the tiny holes in the brain tissue caused by massive cell death – giving it a sponge-like appearance – and allow us to test for the presence of abnormal proteins.
By the end of 1997 there had been 23 confirmed cases of vCJD. The big question was whether this was the start of an epidemic. In similar diseases, such as kuru, there could be a gap of up to forty years between infection and first presentation of symptoms. For once, the media’s scaremongering – Will and Ironside faced a daily barrage of phone calls from journalists – had some scientific foundation.
The number of confirmed cases of vCJD increased over the following few years – in part perhaps because of greater awareness and improved screening methods – but not by much. In all, so far, there have been 176 cases. Still, if vCJD has an average incubation time of 15 or 20 years, we could still be in the shallow part of the epidemiological curve.
The development of a blood test for vCJD was published in the Lancet a year ago. Last week Channel 4 News revealed that the test is now available for use in the UK. There is still no treatment for any form of CJD, but if the test is effective – researchers don’t yet know what the false positive rate is – it should be possible at least to establish more accurately how carriers there are in the UK: current estimates, based on tonsil biopsies, put the number at 1 in 4000, or a total of 15,000.