Prions are responsible for creutzfeldt-Jakob disease (CJD), mad cow disease, scrapie in sheep and kuru in humans. A prion is simple a mis-shaped PrP protein.

Within our bodies we have healthy PrP. However when a mutation occurs or we are infected by an Prion, the unhealthy or scrapie PrP infects our healthy PrP.

Scrapie PrP have a miss shaped tertiary structure.

Scrapie PrP only need to touch a healthy PrP to convert it into a Scrapie PrP.

As you can see by the animation to the left, its easy to see how one prion can have a massive affect on the body.

Prions multiple in numbers and eventually cause death in the CNS. The brain is overwhelmed and can not continue normal function.

The CT scan to the right shows a healthy brain compared to that of a person with CJD.