Cases of Haff disease are seen worldwide, but the causative organisms vary with the geographical location. Burbot, pike, freshwater eel, and whitefish are predominant causative fish in Eastern Europe and Sweden. Cases of Haff disease in China were related to freshwater pomfret and crayfish. In Japan, boxfish was associated with Haff disease, and in the United States, buffalo fish, crayfish, and Atlantic salmon were the culprits.

Initially, more than 1000 cases were linked to the consumption of various species of cooked freshwater fish including burbot, pike, freshwater eel, and whitefish in Eastern Europe and Sweden. In China, cases of Haff disease were reported following consumption of cooked freshwater pomfret and boiled crayfish. Cases in Japan were linked to the consumption of cooked or raw boxfish. In the United States, 29 cases of Haff disease were reported following the consumption of buffalo fish, crayfish, and Atlantic salmon.^[1]