The molecular epidemiology of variant CJD

Abstract

The emergence of the novel prion diseases bovine spongiform encephalopathy (BSE) and, subsequently, variant Creutzfeldt-Jakob disease (vCJD) in epidemic forms has attracted much scientific attention. The oral transmission of these disorders, the causative relationship of vCJD to BSE and the resistance of the transmissible agents in both disorders to conventional forms of decontamination has caused great public health concern. The size of the still emerging vCJD epidemic is thankfully much lower than some early published estimates. This paper reviews current knowledge of the factors that influence the development of vCJD: the properties of the infectious agent; the route of inoculation and individual susceptibility factors. The current epidemiological data are reviewed, along with relevant animal transmission studies. In terms of genetic susceptibility, the best characterised is the common single nucleotide polymorphism at codon 129 of prion protein gene. Current biomarkers and future areas of research will be discussed. These issues are important in informing precautionary measures and the ongoing monitoring of vCJD.

Keywords: BSE; Variant CJD; biomarkers; environmental factors; genetic factors; investigations; prion disease; susceptibility; transmission.

Figure 1

Reported incidence of BSE and vCJD in the UK. Note that the scale on the left is in increments of 5000 cattle. The scale on the right is in increments of 5 vCJD cases.

Figure 2

Published predictions of the size of the vCJD epidemic. The Cooper paper included predictions up to 2010. The Clarke and Garske papers include non-MM cases and subclinical infection as indicated.