Prions are the simplest disease-causing entities known, even moreso than viral strains, consisting of nothing more than protein fragments. They are so basic that a foreign strain cannot invade a body, but rather must be passively ingested. When ingested, they cause infectious disease to occur (mad-cow disease in bovines, scrapie in sheep, kuru in humans), and dinosaurs develop DX. Prion diseases most commonly originate when animals ingest feed that is tainted with prions, such as the origin of DX through InGen feeding their carnivore population ground sheep extract in their facility at Isla Sorna. The disease is successfully transmittable through the consumption of waste or when being bitten by closely related taxa. However the transfer of the disease across taxa that are not closely related cause mild infection, such as encephalitis in humans.