PAUL CLARKE (Department of Infectious Disease Epidemiology, Imperial College London)

New predictions of the British vCJD epidemic

[This meeting is part of the Royal Statistical Society's contribution to National Science Week 2005, a nationwide programme of scientific events and activities.   The Press Release can be seen here.]

Variant Creutzeldt-Jakob disease (vCJD) was first identified as a new disease in 1996 and is thought to be caused by the same aetiological agent behind bovine spongiform encephalopathy in cattle.  There have been 147 deaths from vCJD in all, but the number of new deaths has been declining steadily since the peak of 28 cases in 2000 to 8 in 2004.

However, recently published results estimate the prevalence of vCJD infection to be 235 per million, a much higher figure than had been expected.  These results challenge some of the key assumptions about vCJD used in mathematical and statistical models for predicting the size of epidemic.  In particular, it has been assumed that everyone infected will eventually develop clinical vCJD and die, and that only those people who are methionine homozygous at codon 129 of the prion protein gene are susceptible.

In this presentation, I shall talk about how we extended previous models for the vCJD epidemic to relax these assumptions, and the implication this has for predictions of the epidemic size.  I shall also talk about the possibility of a secondary vCJD epidemic via blood transfusion and other routes, and introduce mathematical models to predict the size of such an epidemic.

Some references:

• Clarke P, Ghani AC. Projections of the future course of the primary vCJD epidemic in the UK: inclusion of subclinical infection and the possibility of wider genetic susceptibility. Journal of the Royal Society Interface 2005 (in press; published online http://www.pubs.royalsoc.ac.uk/interface_homepage.shtml).
• Hilton DA et al. Prevalence of lymphoreticular prion protein accumulation in UK tissue samples. The Journal of Pathology 2004; 203: 733-9.
• Llewelyn CA et al. Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion. The Lancet 2004; 363: 417-21.
• Peden A et al. Preclinical vCJD after blood transfusion in a PRNP codon 129 heterozygous patient. The Lancet 2004; 364: 527-8.

Poster for this event

Paul's PowerPoint slides