Scrapie (/ˈskreɪpi/) is a fatal, degenerative disease affecting the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), and as such it is thought to be caused by a prion. Scrapie has been known since at least 1732 and does not appear to be transmissible to humans. However, new studies suggest a link between scrapie and sporadic CJD. Scrapie usually affects sheep around three to five years of age. The potential for transmission at birth and from contact with placental tissues is apparent.