August 10, 2017


Chinese liver fluke parasite found in farmed pangasius in Vietnam



Scientists from the Norwegian National Institute of Nutrition and Seafood Research (NIFES) have found the parasite Chinese liver fluke in farmed pangasius in Vietnam.


They said the discovery was "surprising". 'We did not expect to find Chinese liver fluke. This is a new parasite species for the Mekong Delta,' said NIFES scientist Arne Levsen, who, together with Vietnamese scientists, did a parasitological study that analysed farmed pangasius in Vietnam.


The Chinese liver fluke is a dangerous parasite that can be transferred to people through consumption of raw or only lightly processed freshwater fish from China and Southeast Asia. In the human body, Chinese liver fluke thrives in the gall bladder and the bile ducts of the liver.


"Serious infections with hundreds of flukes can cause inflammation and blockage of the bile ducts, often with jaundice-like symptoms. In a worst-case scenario, the parasite can even cause liver cancer", Levsen explained.


Because of the finding, Levsen advised tourists visiting Vietnam and Southeast Asia to avoid local, only lightly processed fish dishes, as proper heating is required to kill the parasites.




"If you do not know if the seafood you're offered has undergone proper heat treatment, don't eat it. This goes for all seafood, including crabs and prawns, which may contain other parasites that can be dangerous", he said.


Besides analysing 865 farmed fish, the scientists checked 130 wild pangasius from basically the same area for parasites.


But no Chinese liver flukes were found in the wild fish. As to where the parasite came from, Levsen said they were trying to find out.


"Our present working hypothesis is that the parasite was brought along with broodstock from areas where the parasite occurs naturally.


"It probably originates in other regions of Southeast Asia such as Thailand or South China. We are now comparing various genes to check if there are any genetic footprints that enable us to trace the flukes back to their area of origin", the NIFES scientist said.

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