Here, ingestion of the parasite's larvae is not necessary for the disease to occur - those affected become sensitive to Anisakis proteins that come into contact with the skin or respiratory tract. Some workers in the fishing industry as well as cooks and other professionals who regularly deal with fish may suffer from occupational allergic anisakiasis. Infection of the small intestine is less common, but when it occurs it can result in an inflammatory mass and symptoms similar to Crohn's disease, which develops one to two weeks later. Other symptoms can include allergic reactions and even anaphylactic shock. The most typical symptoms of gastric anisakiasis include abdominal pain, nausea and vomiting within hours of ingesting the larvae. While the parasite cannot reproduce in humans, it can survive for a short period of time and cause anisakiasis, which can range from mild to severe depending on the person infected. Once ingested, they settle in our stomach and sometimes the small intestine. When we consume fish, squid, octopus or other seafood containing third-stage Anisakis larvae that's raw or undercooked, we can become accidental hosts to Anisakis larvae. When the krill are in turn eaten by fish or squid, another stage of larvae infects the predators' guts and become embedded on the surface of their organs and eventually in their muscles.Īnd that's where we humans come in. There, krill - small crustaceans that form the basis of the ocean food chain - eat them and become infected with larval stages of the nematodes. The parasite's eggs are expelled along with the animal's feces and hatch in seawater. These nematodes infect a wide range of marine organisms fish and cephalopods serve as intermediate hosts, while dolphins, whales, seals and other marine mammals are the final hosts.Īdult worms are found in the mucous membrane that lines the stomachs of marine mammals. The genus Anisakis comprises nine species, three of which ( Anisakis simplex, Anisakis pegreffii and Anisakis physeteris) have been confirmed as zoonotic pathogens. So how can this troublesome disease be avoided? The answer lies in understanding the parasites' life cycle. Today, anisakiasis is not only an emerging global human health problem, but it is also an economic concern, due to the potential negative effects on consumer confidence and trade associated with infected fish products. In Japan alone, where it is traditional to eat raw fish and seafood dishes, more than 7,000 cases of anisakiasis occur annually. Every year and on all continents, countless cases are diagnosed in humans, in part because the rise in consumption of foods such as sushi and sashimi. The parasitic disease anisakiasis, caused by nematode larvae belonging to the genus Anisakis, is considered the main threat to human health. As a consequence, they're the focus of much of the world's medical and economic concern. Of more global concern are those caused by some nematodes of the family Anisakidae, particularly species of the genera Anisakis, Pseudoterranova and Contracaecum. The World Health Organization estimates that some 56 million cases of parasitic infections associated with the consumption of fish products occur annually.Īmong the fish-borne parasites that can affect humans, there are three major groups of parasitic worms, also known as helminths: flatworms, spiny-headed worms (acanthocephalans) and ciliated worms (nematodes).ĭiagnoses of infection with Opisthorchis, a family of flatworms, are the most common, but they occur mainly in East and Southeast Asia. Every year, almost one in ten people fall ill from eating contaminated food. Appealing as such dishes can be, they can also increase the risk of exposure to fish-borne parasites. article was originally published on The Conversation.įrom sushi and sashimi (Japan) to poke bowls (Hawaii) and ceviche (Peru), consumption of raw or undercooked fish and other seafood is becoming increasingly popular.
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