Anisakiasis & Anisakis : Infection, Diagnosis, Symptoms, Treatment & Prevention


Anisakiasis may be a human parasitic infection of the alimentary canal caused by the consumption of raw or undercooked seafood containing larvae of the nematode worm Anisakis simplex. Fish, squid, and crustaceans typically act as transport host during which larvae grow however don’t mature into adults. Once larger marine mammal like seals, sea lions, dolphins and whales consume these smaller fish and crustaceans, the larvae change into adult worms. In humans, larvae are unable to complete their development and cause infection. Symptoms of Anisakiasis embraces violent abdominal pain, nausea and vomiting. In some cases, antigens present in Anisakis simplex will turn out hypersensitive reactions and hypersensitivity. Most human infections are reported from Japan, Holland, and Spain.


The first case of human infection by a member of the family Anisakidae was rumoured within the Netherlands by Van Thiel who delineate the presence of a marine nematode worm in a patient affected by acute abdominal pain. The nematode worm was later known as Anisakis spp. and also the human infection was termed Anisakiasis. Japanese authors have delineated the majority of cases, though cases are rumoured in Korea, Holland, Germany, Spain, Italy, and also the United States among others. The majority of infections involve a gastric or intestinal invasion. Tissue injury happens due to the invasion of the gut wall, development of white blood cell granuloma, and perforation. Invasive gastric Anisakiasis is characterized by the abrupt onset of abdominal pain, nausea, typically vomiting or diarrhoea with signs of peritoneal irritation and incomplete obstruction of the little intestine. Invasion of the little intestine ends up in lower abdominal pain and signs of obstruction. Symptoms will occur from as very little as an hour to 2 weeks once consumption of raw or undercooked food and might persist for months, rarely for years. If larvae pass into the intestine, a severe white blood cell granulomatous response could occur one to 2 weeks once infection that mimic Crohn’s illness. Acute allergic manifestations of roseola and anaphylaxis could occur with or while not related channel symptoms. The frequency of allergic symptoms in connection with fish consumption has resulted in the conception of gastro-allergic Anisakiasis, an acute IgE-mediated generalized reaction. Occupational allergic reaction together with the asthma attack, conjunctivitis, and make contact with dermatitis has been determined in fish process employees. An additional benign type of infection, called transient Anisakiasis, happens with no symptoms or mild throat irritation and also the larva is often coughed up. These transient infections typically go undiagnosed.



Being representative of internal organ nematodes, Anisakis are nonparasitic, non-segmented, cylindrical worms. Worms have each an oral and an anal gap additionally as an entire digestive tract that features an oesophagus, a pocket, and an intestine. In addition, third stage larva has the subsequent characteristics: 3 bilobed lips, one dorsal and 2 ventrolateral; a boring tooth ventral to the mouth, and a discharge pore between the ventrolateral lips. Larva could reach a length of 50mm and a diameter of one to 2mm. Classification of the larva of Anisakis is completed on the premise of the structure of the digestive tract. Marine mammals discharge unembryonated eggs created by female larvae. Eggs become embryonated in water, forming initial stage larva that moults to become second stage larvae. Larvae hatch from the eggs and become unattached. Unattached larvae are eaten by crustacean, wherever they grow to be infective third stage larvae. If infected crustaceans are eaten by fish, the larvae will penetrate into the body cavity and/or muscles of that host. Fish and squid act as a paratenic host within which larvae will grow however don’t become adults. Once infected fish are eaten by marine animals, third stage larvae become adults. Humans are unintentional hosts, the parasites cannot mature or reproduce in humans.

Symptoms of Anisakiasis

Common signs and symptoms of Anisakiasis are:

  • Abdominal distention
  • Vomiting
  • abdominal pain
  • nausea
  • Blood and secretion in a stool, and delicate fever.
  • Diarrhoea, allergic reactions with rash and itchiness, and often, anaphylaxis, can even occur.

Diagnosis of Anisakiasis

A presumptive identification is also created by examining a patient’s food habits and exposure to raw or raw food. A definitive diagnosing is made by obtaining and visualizing worms through endoscopy, at surgery, or in patient’s vomit a histopathological study of gastric or intestinal tissue may also be useful in determining the presence of worms. To its imprecise symptoms, Anisakiasis is commonly misdiagnosed as appendicitis or Crohn’s illness, however, larger awareness and development of upper diagnostic tools has led to increased reporting of Anisakiasis in many parts of the planet besides the United States. Sensitization and hypersensitive reaction are determined by skin-prick check and detection of specific antibodies against Anisakis. Hypersensitivity is indicated by a quick rise in levels of IgE among the initial several days following consumption of infected fish. Serodiagnostic tests available for Anisakis reactivity include latex-based agglutination procedures, and immunoelectrophoresis, immunofluorescence, indirect haemagglutination, immunologic response, immunoblotting, and ELISA.

Treatment of Anisakiasis

Because humans are the inactive host of Anisakis, no treatment is required in most cases. Endoscopy and surgery serve to verify the designation and to produce a treatment. Treatment with albendazole, 400 mg double daily for twenty-one days, has been used with success in patients. For patients with the allergic reaction, modification of diet to exclude fish are often accustomed manage symptoms.


Prevention of Anisakiasis

Raising client and producer awareness concerning the existence of Anisakis worms in fish could be a vital and effective prevention strategy. Anisakiasis may be simply prevented by adequate preparation at temperatures greater than sixty degrees or temperature reduction. The government agency recommends that everyone shellfish and fish meant for raw consumption be blast has frozen to -35°C or below for fifteen hours or be frequently frozen to -20°C or below for seven days. Salting and marinating won’t essentially kill the parasites. Anisakis worms represent a biological hazard for the fishing business. The larva will continue fish that has not been frozen immediately when being caught. Current European Community laws on fish and food need the visual examination of fish, extraction of visible parasites, and removal of heavily parasitized fish from the market. The mandate to freeze herring within the Netherlands has just about eliminated human Anisakiasis.


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