An assumption that most people have a genetic resistance against variant Creutzfeldt-Jakob-Disease (vCJD) could be wrong. This comes from two recent scientific studies suggesting that the incubation time of vCJD could be much longer that originally believed making detection even more difficult.

John Collinge from University College London and his colleagues analyzed cases of Kuru, a human prion disease which occurs in Papua New Guniea and is transmitted by cannibalistic rites. The researchers found out, that the incubation times of Kuru, can easily exceed 50 years. The incubation time of vCJD could even be much longer as a inter-species transmission from animals to humans is less effective than a transmission between humans.

A study conducted by John Collinge and colleagues from University College in London analyzed cases of Kuru, a human prion disease occurring in Papua New Guniea and transmitted by cannibalistic rites. The researchers discovered that incubation times of Kuru can easily exceed 50 years. These findings indicate that the incubation time of vCJD could be even longer because inter-species transmission from animals to humans is less effective than a transmission between humans.

vCJD prevalence underestimated
A second study by the research group of James W. Ironside of the National Creutzfeldt-Jakob Disease Surveillance Unit, University of Edinburgh, reports on the identification of prion infected individuals by analyzing appendices and tonsils removed during routine surgery. Evidence to date suggests that in general people with at least one valine (V) encoded on codon 129 of the prion gene were thought to be less prone if not resistant to prion infection. However, the study of Ironside and colleagues, show that vCJD infected people in fact can carry a valine genotype that has been assumed to be resistant to prion disease. This latest study has raised major concerns that vCJD prevalence may be underestimated. Ironside and his colleagues estimate that in the worst-case about 3800 people in the U.K. currently incubate vCJD.

Need for prion blood test
Long incubation times and a high number of infected people may result in an accelerated spread of the disease, for example via contaminated surgical instruments or blood donations. Once a critical mass of people is infected, the disease can spread and - when no measures are taken - reach epidemic levels. This scenario can be hopefully avoided by the availability of a prion blood test in the near future.