Warning over salmon parasite that can be fatal

Charles Clover, Telegraph 25 Jan 08;

Wild salmon caught in Britain are carrying increased amounts of a parasite dangerous to humans, the Food Standards Agency has warned.

The Agency has issued safety guidelines to people who eat their own catch or sell it locally after increased levels of the parasite, anisakis simplex, known in the United States as herring worm, were found.

The parasite can cause severe anaphylactic reactions in some people, with symptoms including erratic heartbeat and respiratory failure. These can, in some cases, be fatal.

The Agency says cases are rare but there were two last year and one the year before.

The salmon pick up the parasite when feeding on krill at sea. It causes the fish's vents to swell and bleed, which it is feared could lead to a collapse in the numbers of salmon spawning successfully.

The Agency says that people must freeze wild salmon for at least 24 hours to kill the parasite at a temperatue of - 20°C or colder if it is to be eaten raw or almost raw.
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This advice applies to salmon that are to be smoked cold or eaten after marinating or salting, as in Gravadlax.

If it is to be cooked, the salmon should reach 70°C for at least two minutes.

As the larvae of the parasite cannot be identified and removed, this advice is particularly important for elderly people and pregnant women.

Fish which are obviously contaminated should not be consumed, according to the Agency.

The Environment Agency has said that record numbers of salmon were found to be carrying the parasite last year. On the Itchen in Hampshire, as many as 30 per cent of salmon had the disease.

It was also found in the rivers Exe, Dee, Taff, Camel, Tamar, Eden Tyne, Ribble, Wye and Lune and in a number of Scottish rivers.

Officials from the agency say that the evidence is at present inconclusive whether the parasite could bring about the collapse of salmon populations.

David Browse, head of the Hampshire Salmon Trust, said: "I hope we're wrong but we have already found dead salmon that haven't spawned."

Luckily, the parasite has struck the Itchen when it has three times the usual number of salmon coming into the river. Anglers think this is due to the winding-down of drift netting for salmon in the Irish Sea.