Dear Gregg
Parasites harmful to humans can be found in freshwater fish. They come from
the phylum Platyhelminthes, classes Cestoda and Trematoda.
Cestodes are tapeworms and the species of major concern associated with
consumption of fish is the fish tapeworm, Diphyllobothrium spp.,
particularly D. latum. Humans, along with other fish-eating mammals, are one
of the definitive hosts, and freshwater copepods and fish are the
intermediate hosts. It found in fish in temperate waters including in North
America.
Trematodes, commonly called flukes, are responsible for a variety of
parasitic diseases some of which are transmitted through fish and shellfish.
The most important parasites, so far as numbers of people affected is
concerned, transmitted by freshwater fish and shellfish are species of the
genera Clonorchis, Opisthorchis, and Paragonimus. They all have similar life
cycles involving a definitive host and two intermediate hosts. The
definitive host is man and other mammals. The first intermediate host is a
freshwater snail, and the second a fish or crustacean shellfish. They snail
intermediate hosts are found in warm waters, above about 20ºC, and limits
infection to fish in warm waters. Man and animals are infected by eating
raw, or minimally processed, fish or shellfish.
You will need to consult specialist texts on parasitology for methods for
isolation and identification of the parasites.
Some literature:
Deardorff, T.L. & Overstreet, R.M., 1991, Seafood-transmitted zoonoses in
the United States: the fishes, the dishes, and the worms, Microbiology of
Marine Food Products, D.R. Ward & C. Hackney, eds, Van Nostrand Reinhold,
New York, pp 211-265. ISBN 0 442 23346 9
Harinasatu, T., Pungpak, S. & Keystone, J.S. (1993). Trematode infections.
Opisthorchiasis, clonorchiasis, fascioliasis, and paragonimiasis. Infectious
Disease Clinics of North America, 7, 699-716
Malek, E.A. (1980). Snail-transmitted Parasitic Diseases, vol II. CRC Press,
Inc., Boca Raton, USA.
Rim, H-J. (1982). Clonorchiasis. In: CRC Handbook Series in Zoonoses,
Section C: Parasitic Zoonoses, G.V. Hillyer & C.F. Hopla, eds, CRC Press,
Boca Raton, USA, pp 17-32.
Rim, H-J., Farag, H.F.,Sornami, S. & Cross, J.H. (1994). Food-borne
trematodes: ignored or emerging. Parasitology Today, 10, 207-209.
Rodger, H.D. (1991). Diphyllobothrium sp. infections in freshwater-reared
Atlantic salmon (Salmo salar L.). Aquaculture, 95, 7-14.
Rodrick, G.E. & Cheng, T.C. (1989). Parasites: occurrence and significance
in marine animals. Food Technology, (11), 98-102.
WHO (1995). Control of Foodborne Trematode Infections. WHO Technical Report
Series 849. World Health Organization , Geneva.
Von Bonsdorff, B. (1977). Diphyllobothriasis in Man. Academic Press, London.
WHO (1995). Control of Foodborne Trematode Infections. WHO Technical Report
Series 849. World Health Organization , Geneva.
Peter Howgate
----- Original Message -----
From: Seafood Inspection Services <gregg@fishinspector.com>
To: <seafood@ucdavis.edu>
Sent: Thursday, July 25, 2002 6:13 AM
Subject: parasites (fresh water fish)
> Hello,
>
> Can someone please advise as to whether or not parasites are common in
fresh
> water fish.
>
> If so, can you direct me to any resources which would aid in their
> identification.
>
>
> Thank you,
>
> Gregg
>
>
>
>
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