Pathogens responsible for a neurodegenerative disease in sheep and goat can cross the species barrier to infect humans with a disease similar to Creutzfeldt-Jakob disease, says an INRA study.

But this is not a major risk for public health as cases of CJD are rare even though scrapie has been circulating for centuries, say the researchers.

Similar to Bovine Spongiform Encephalopathy (BSE) or mad cow disease, scrapie is caused by a transmissible pathogen protein called prion.

Human transmission of BSE was shown in 1996.

While epidemiological studies so far have not been able to establish a link between this disease and the occurrence of prion diseases in humans, the latest work calls for a reassessment.

Researchers at INRA led by Olivier Andreoletti, studied the permeability of the human transmission barrier to scrapie-causing pathogens by using mouse models.

The approach was the same that had shown the zoonotic nature of prions responsible for BSE in cows and of the variant of Creutzfeldt-Jakob disease in humans (vCJD).

The results showed that some pathogens were able to cross the transmission barrier.

Those pathogens that crossed the barrier were undistinguishable from the prions causing the sporadic form of Creutzfeldt-Jakob disease (sCJD).

The primary results have been published in Nature Communications.