Histamine and other biogenic amines
Histamine is an organic nitrogen compound that may trigger an allergic response in human and mammalian systems. Other biogenic amines (such as cadaverine and putrescine) are thought to potentiate the toxic effect of histamine. Although fatal cases are rare, severity of the symptoms can vary depending on the amount of histamine and other biogenic amines ingested and the individual’s sensitivity to specific biogenic amines.
Scombroid fish poisoning (often called "histamine poisoning") is caused by ingestion of certain species of marine fish that contain high levels of histamine and possibly other biogenic amines. These fish species contain high levels of free histidine in their tissue and when such fish are subjected to temperature abuse after harvest, bacteria decarboxylate histidine to produce histamine. A number of bacterial species can produce histamine, but Morganella morganii and Proteus spp. are particularly strong histamine producers.