Very low oral exposure to prions of brain or saliva origin can transmit chronic wasting disease.
Denkers ND, Hoover CE, Davenport KA, Henderson DM, McNulty EE, Nalls AV, Mathiason CK, Hoover EA. Very low oral exposure to prions of brain or saliva origin can transmit chronic wasting disease. PLoS One. 2020; 15(8):e0237410.