Prions are infectious proteins that cause diseases in humans and other animals. Studies so far have suggested that insects, poultry and scavengers like crows may be passive carriers of infectious prions, but this is the first demonstration that prions can retain their ability to cause disease after passing through the avian digestive system.
The authors fed crows with brain samples from mice infected with prions, and found that the crows passed infectious prions up to 4 hours after eating the infected samples. When healthy mice were injected with the infected crow excretions, all the mice showed signs of prion disease. The authors state that their results support the possibility that crows that encounter infected carcasses or consume infected tissue may have the capacity to transport infectious prions to new locations.