Symptoms and pathology produced by toxic Microcystis aeruginosa NRC-1 in laboratory and domestic animals.

Toxicity tests with lyophilized M. aeruginosa NRC-1 cells have been conducted using mice, guinea pigs, rabbits, chickens, ducks, two calves and one lamb as the test animals. The symptoms and pathological changes are described. On an equivalent weight basis it required three to five times the oral dosage to kill the large animals and birds as it did to kill the laboratory animals. The symptoms were less pronounced and the survival times were longer in the more resistant animals. Enlargement and congestion of the liver with necrosis of the hepatic cells were constant and pathognomonic. These findings are in general agreement with the observations of other workers who have examined the toxicity of naturally occurring Microcystis waterblooms. The toxicities and structures of microcystin and of six other biologically active cyclic polypeptides are summarized. The pathological effects produced by microcystin in laboratory and domestic animals resemble those produced in man but differ from those produced in animals by the toxic peptides of Amanita phalloides.