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Parasites in fish are harmless!

Parasites in fish are harmless!. Erlingur Hauksson Facts about the most common or conspicuous parasites found in commercially important fish and fish-products. Parasites in fish. Micro-organisms , which can cause disintegration of the fillets when the fish is cooked, such as Kudoa sp.

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Parasites in fish are harmless!

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  1. Parasites in fish are harmless! • Erlingur Hauksson • Facts about the most common or conspicuous parasites found in commercially important fish and fish-products

  2. Parasites in fish • Micro-organisms, which can cause disintegration of the fillets when the fish is cooked, such as Kudoa sp. • Ectoparasitic crustaceans, such as Sphyrion lumpi on oceanic redfish • Platyhelminthes, mostly in freshwater fish • Nematodes, mostly in marine fish

  3. Sphyrion on oceanic redfish

  4. Sphyrion is common on oceanic redfish • Prevalence of Sphyrion on oceanic redfish is 14-39% • The “head” of this parasite cause the fish-industry trouble. Its remains has to be picked out of the fillets • Female fish are more infected than males • The life-cycle of Sphyrion is unknown

  5. Sphyrion infections have decreased in redfish 1989 to 1993 % For 1989 no information of infestation of fish in relation to sex is available

  6. Nematodes • Nematodes are parasites of fish and other marine animals • Parasitic nematodes reproduce in final hosts and infect other marine animals (intermediate hosts) when they are swallowed with food • Life-cycles of marine parasitic nematodes, are complicated, involving many hosts

  7. Life-cycle of the sealworm

  8. Life-cycle of the whaleworm

  9. Are nematodes harmless? • Sealworms are not dangerous for humans They are as nutritious as fish. There are no cases of sealworm making people seriously ill • Whaleworms seem more dangerous. They have caused people illness (anisakiasis) • Persons getting ill of anisakiasis had consumed raw fish

  10. Whaleworms in cod liver

  11. Nematodes in a fillet of cod

  12. Nematodes and fish-processing • Nematodes tolerate weak saline solutions quite well. They can survive for months in 2,5% solution at 10 °C • More concentrated salt solutions kill them in short time, depending on the strength • Nematodes do not survive heat above 60 oC, so boiling surely kills them • They can not survive freezing. After one day in 20 oC, they are all dead

  13. Nematodes and the fish-market • Nematodes in fish are a constant threat to marketing of fish • About 5% of the total number of nematodes are still left in the fillets after inspection and cleaning on a candling table • Sale of fish products decreased about 30% after a TV-program on nematodes in fish was shown, in W-Germany 1987

  14. Solution to the problem • Technical solutions of the nematode-problem, are still on the drawing table • One (biological) solution, would be to reduce the population of the grey seal. Total number of nematodes in cod has decreased following a reduction in the grey seal population in Iceland

  15. Nematodes in cod 1973-1996

  16. Concluding remarks • Parasites in Icelandic fish are not dangerous to people • The whaleworm is the only exception • Raw, lightly smoked, and marinated fish-dishes, which could be infected with whaleworm, have to be prepared and consumed with carefulness • Parasites do not make fish a dangerous food. Fish is a very healthy food

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