How widespread is variant Creutzfeldt-Jakob disease?

Variant Creutzfeldt-Jakob Disease (CJD) is the human form of bovine spongiform encephalopathy or “mad cow disease.” It is one of the family of mainly neurodegenerative diseases known as spongiform encephalopathies because of their histological appearance. These diseases afflict animals and humans and are widely accepted as resulting from the toxic build-up of an aberrant form of a normal cellular protein, the prion protein. Bovine spongiform encephalopathy was common, with more than 36 000 cases in the peak year of the cattle epidemic in the United Kingdom (1992).1 However, variant CJD has remained mercifully rare, with 177 cases in the UK to date (51 in the rest of the world, 27 of which were in France), and only one in the past two years.2

So, is variant CJD yesterday’s news? The linked paper by Gill and colleagues (doi:10.1136/bmj.f5675) helps make clear why this is not the case.3 Sporadic CJD, the “usual” form of CJD, was first described early last century and is found worldwide, with an annual incidence of around 1/1 000 000 population. Prion infectivity is notoriously difficult to inactivate and sporadic CJD had been shown to …