The findings are the latest to suggest that these universally fatal, if rare, diseases can be spread through the eyes.
We can get sick from prions in a few ways. Sometimes, people are born with mutations passed down in their family that increase the risk of developing a prion disease, including a form of CJD. Most commonly, as with people who have sCJD, the prions show up spontaneously, with the normally harmless prion protein changing into a misfolded form that makes nearby proteins misfold, too. But what’s especially terrifying about prions is that they can also be infectious, capable of spreading from person to person, or even animal to person.
It can take years, even decades, for the symptoms of a prion disease (such as dementia or muscle weakness) to show up, but once they do, it’s usually only a matter of months before death.