Potential parasitic hazards for humans in fish meat

Aquatic organism play important role in expending economy of a country in terms of food production and demand for aquaculture meat is day by day increasing.

Fish are the most residents of the ocean. Fish are vertebrates’ animals living in water. Fish meat is rich of all essential nutrients and mainly essential fatty acids. That is why demand for fish meat increasing continuously.

But consumption of raw fish meat has serious safety concerns due to parasitic hazard. Good knowledge and expertise help in removal of hazards related to consumption of fish meat. Fish meat should be cooked properly to avoid fishborne parasitic infection.

Parasites

 Fish species are widely affected by parasitic infection, specifically in areas where human and animal waste is used as fish feed in fish pounds. Some of these parasites cause life threatening condition in humans. Majorly there are three main classes of parasites in which nematode and trematode having high chances of disease than cestodes.

Nematodes  

 Normally nematodes are nonzoonotic but some time they cause serious threat to human health. Among all the nematodes Anisakis spp.  Has the largest medical importance due to heavy allergic reactions and abdominal pain. It causes these effects on humans after eating the raw fish or crustaceans. These signs are common in areas where raw or undercooked meat is consumed.

Anisakiasis is a zoonotic problem in world and increases continuously in the last 20 years. North Asia and Western Europe are more affected. Fish imported to Serbia is affected by Anisakis. In the period 2000-2013, 2414 samples inspected. 25 species of Anisakis and herring found infected. Pseudoterranova decipiens causes human disease. Larva of A.

simplex infects human being by consuming raw and uncooked salmon, cod and herring. A. simplex larvae penetrate gastric membrane in human and cause abscess. Other organs and peritoneal cavity also affected. Some nematodes excreted through faeces instead of penetrating gastric mucosa.

Eustrongylides spp is more common freshwater fish zoonotic nematodes. Gastric and intestinal pores are formed in humans using raw or uncooked fish meat infected with Eustrongylides. Pathogenicity in case of humans is different from birds.

Trematodes

18 million peoples are infected by fish-borne trematodes in world. Half a billion peoples are at risk in developing countries. 33 species of trematodes are transmissible to human by eating crustacean and fish. But some causes zoonotic problems. Peoples of Middle East and Asia are more affected.

When large number of trematodes accumulate in intestine causes swelling and erosion of intestinal mucosa. In East Asia and Eastern Europe the major threat is due to Liver fluke. Cyprinidae fish species are intermediate hosts of C.sinensis and Opisthorchis spp. C.

Sinensis naturally infect more than hundred species of freshwater fish while Opisthorchis infect 35 species. No any specific symptoms are shown by patients while in nonspecific symptoms abdominal pain and fatigue occurs in some peoples. Gall bladder increases in size along with cholangitis and enlarged liver.

Ideas for decreasing the parasitic threats in fish meat        

Consumption of raw or undercooked meat play major role in fishborne parasitic zoonoses. Actually the cases of foodborne diseases caused by utilization of fish are less as compare to dairy, poultry and meat products. This threat is prevented by observation and removal of visible parasites. Fish and fish meat products should be properly monitor and inspect before being placed on the market.

Freshwater should free of any parasitic infection. Control of first intermediate host helps us in prevention of parasitic infection by controlling surface water environment (hygienic aquaculture). Parasites can be killed by heating, freezing, and proper ratio of salt content and storage time. Cold and hot smoking is also use for reduction of parasite threat in fish.

But these cannot remove parasites completely. Raw or poorly cooked meat consumption should be avoided, is the best strategy for prevention. Imported fish species should be monitor at regular basis. Fish food preparation and consumption should be in such a way that hazard to human health is least. People’s awareness also helps in fighting against fishborne zoonotic infections.

Authors: Muhammad Tahir¹, Rao Zahid Abbas¹, Zohaib Saeed¹, Mudassar Mehmood¹

1. Department of Parasitology, University of Agriculture, Faisalabad, Pakistan