In vitro inactivation of Clostridium botulinum toxins types B, C and E by digestive juices of man and ducks.

Inactivation of botulinum toxins type B-L, B-M, C-L and E in the digestive juices of man and ducks was determined. Botulinum toxins of the M size (B-M and E) lost their toxicity completely in the gastric juices of both man and ducks, but toxins of the L size (B-L and C-L) lost their toxicity only partially. The toxins were hardly affected by duodenal fluid even after exposure to gastric juice. The toxins were not inactivated by cecal fluid from ducks. Since human digestive juices and those from ducks appeared to have comparable effects on the inactivation of toxin, differences in susceptibilities of the animal species to orally acquired toxins are in all probability not caused by digestive action of those species.