from Sunday Herald, 14 October 2007
The government's food safety watchdog has issued a warning about the spread of a potentially dangerous parasitic worm infecting wild salmon.
The nematode worm, known as anisakis, can cause severe illness if eaten, including violent abdominal pain, vomiting and anaphylactic shock. The disease it causes, anisakiasis, is often reported where raw fish is eaten, such as sushi in Japan.
This summer the tiny worm has been detected in 23 Scottish salmon rivers, and is thought to be far more widespread than usual. The worms feed on salmon's rear ends, causing 'bleeding vent syndrome'.
The Food Standards Agency (FSA) has issued guidance (48KB pdf) for anglers and netsmen who eat their catch or supply local retailers. "Parasites in fish, particularly anisakis, can, if ingested alive, cause serious health problems," the agency says.
If salmon is to be eaten raw, cold-smoked or marinaded, the FSA recommends freezing it below minus 20 degrees centigrade for at least 24 hours to kill the worms. When it is hot-smoked to reach an internal temperature of 60 degrees centigrade, it should also be safe to eat.
Otherwise the salmon should be cooked at 70 degrees centigrade for two minutes to kill the parasites. "This advice is particularly relevant for pregnant women and elderly people, where ingestion of live parasites from fish could pose a serious health risk," adds the FSA.
The FSA's new advice is welcomed by angling organisations. "The high incidence of fish caught this year with bleeding vents has been a source of concern to fisheries managers and anglers," says Andrew Wallace, managing director of the Association of Salmon Fishery Boards.
"The phenomenon has been witnessed in stocks in previous years but the 2007 grilse stock seems to have been particularly badly affected. This highlights the need to better understand the influences on the Atlantic salmon's life at sea which still remains something of a mystery."
The situation need to be closely monitored for the remainder of the year and in the future, Wallace argues. "Particular care seems to be advisable in the handling and preparation of uncooked salmon."