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Anisakis is a genus of parasitic nematodes, which have life cycles involving fish and marine mammals.^[1] They are infective to humans and cause anisakiasis. People who produce immunoglobulin E in response to this parasite may subsequently have an allergic reaction, including anaphylaxis, after eating fish that have been infected with Anisakis species.

Etymology

The genus Anisakis was created in 1845^[2] by Félix Dujardin as a subgenus of the genus Ascaris Linnaeus, 1758. Dujardin did not explicit the etymology but stated that the subgenus included the species in which the males have unequal spicules ("mâles ayant des spicules inégaux"); thus the name Anisakis is based on anis- (Greek prefix for different) and akis (Greek for spine or spicule). Two species were included in the new subgenus, Ascaris (Anisakis) distans Rudolphi, 1809 and Ascaris (Anisakis) simplex Rudolphi, 1809.

Life cycle

Complex life cycle of Anisakis worms

Anisakis species have complex life cycles which pass through a number of hosts through the course of their lives. Eggs hatch in seawater, and larvae are eaten by crustaceans, usually euphausids. The infected crustacean is subsequently eaten by a fish or squid, and the nematode burrows into the wall of the gut and encysts in a protective coat, usually on the outside of the visceral organs, but occasionally in the muscle or beneath the skin. The life cycle is completed when an infected fish is eaten by a marine mammal, such as a whale, seal, or dolphin. The nematode excysts in the intestine, feeds, grows, mates and releases eggs into the seawater in the host's feces. As the gut of a marine mammal is functionally very similar to that of a human, Anisakis species are able to infect humans who eat raw or undercooked fish.

The known diversity of the genus has increased greatly over the past 20 years, with the advent of modern genetic techniques in species identification.^[3] Each final host species was discovered to have its own biochemically and genetically identifiable "sibling species" of Anisakis, which is reproductively isolated. This finding has allowed the proportion of different sibling species in a fish to be used as an indicator of population identity in fish stocks.

Morphology

A scanning electron micrograph of the mouthparts of A. simplex

Anisakids share the common features of all nematodes; the vermiform body plan, round in cross section and a lack of segmentation. The body cavity is reduced to a narrow pseudocoel. The mouth is located anteriorly, and surrounded by projections used in feeding and sensation, with the anus slightly offset from the posterior. The squamous epithelium secretes a layered cuticle to protect the body from digestive juices.

As with all parasites with a complex life cycle involving a number of hosts, details of the morphology vary depending on the host and life cycle stage. In the stage which infects fish, Anisakis species are found in a distinctive "watch-spring coil" shape. They are roughly 2 cm long when uncoiled. When in the final host, anisakids are longer, thicker and more sturdy, to deal with the hazardous environment of a mammalian gut.

Health implications

Anisakids pose a risk to human health through intestinal infection with worms from the eating of underprocessed fish, and through allergic reactions to chemicals left by the worms in fish flesh.^[4]

Anisakiasis

Differential symptoms of parasite infection by raw fish: Clonorchis sinensis (trematode/fluke), Anisakis (nematode/roundworm) and Diphyllobothrium (cestode/tapeworm),^[5] all have gastrointestinal, but otherwise distinct, symptoms. ^[6] ^[7] ^[8] ^[9]

Anisakiasis is a human parasitic infection of the gastrointestinal tract caused by the consumption of raw or undercooked seafood containing larvae of the nematode Anisakis simplex. The first case of human infection by a member of the family Anisakidae was reported in the Netherlands by Van Thiel, who described the presence of a marine nematode in a patient suffering from acute abdominal pain.^[10] It is frequently reported in areas of the world where fish is consumed raw, lightly pickled or salted. The areas of highest prevalence are Scandinavia (from cod livers), Japan (after eating sushi and sashimi), the Netherlands (by eating infected fermented herrings (maatjes)), and along the Pacific coast of South America (from eating ceviche). Fewer than ten cases occur annually in the United States.^[11] Development of better diagnostic tools and greater awareness has led to more frequent reporting of anisakiasis.

Within a few hours of ingestion, the parasitic worm tries to burrow though the intestinal wall, but since it cannot penetrate it, it gets stuck and dies. The presence of the parasite triggers an immune response; immune cells surround the worms, forming a ball-like structure that can block the digestive system, causing severe abdominal pain, malnutrition and vomiting. Occasionally, the larvae are regurgitated. If the larvae pass into the bowel or large intestine, a severe eosinophilic granulomatous response may also occur one to two weeks following infection, causing symptoms mimicking Crohn's disease.

Diagnosis can be made by gastroscopic examination, during which the 2-cm larvae are visually observed and removed, or by histopathologic examination of tissue removed at biopsy or during surgery.

Raising consumer and producer awareness about the existence of anisakid worms in fish is a critical and effective prevention strategy. Anisakiasis can be easily prevented by adequate cooking at temperatures greater than 60°C or freezing. The FDA recommends all shellfish and fish intended for raw consumption be blast frozen to -35°C or below for 15 hours or be regularly frozen to -20°C or below for seven days.^[11] Salting and marinating will not necessarily kill the parasites. Humans are thought to be more at risk of anisakiasis from eating wild fish rather than farmed fish. Many countries require all types of fish with potential risk intended for raw consumption to be previously frozen to kill parasites. The mandate to freeze herring in the Netherlands has virtually eliminated human anisakiasis.^[12]

Allergic reactions

Even when the fish is thoroughly cooked, Anisakis larvae pose a health risk to humans. Anisakids (and related species such as the sealworm, Pseudoterranova species, and the codworm Hysterothylacium aduncum) release a number of biochemicals into the surrounding tissues when they infect a fish. They are also often consumed whole, accidentally, inside a fillet of fish.

Anisakid larvae in the body cavity of a herring (Clupea harengus)

Acute allergic manifestations, such as urticaria and anaphylaxis, may occur with or without accompanying gastrointestinal symptoms. The frequency of allergic symptoms in connection with fish ingestion has led to the concept of gastroallergic anisakiasis, an acute IgE-mediated generalized reaction.^[10] Occupational allergy, including asthma, conjunctivitis, and contact dermatitis, has been observed in fish processing workers.^[13] Sensitivization and allergy are determined by skin-prick test and detection of specific antibodies against Anisakis. Hypersensitivity is indicated by a rapid rise in levels of IgE in the first several days following consumption of infected fish.^[10]

Treatment

For the worm, humans are a dead-end host. Anisakis and Pseudoterranova larvae cannot survive in humans, and will eventually die. In some cases, the infection will resolve with only symptomatic treatment.^[14] In other cases, however, infection can lead to small bowel obstruction, which may require surgery,^[15] although treatment with albendazole alone (avoiding surgery) has been reported to be successful. Intestinal perforation (an emergency) is also possible.^[16]

Occurrence

Larval anisakids are common parasites of marine and anadromous fish (e.g. salmon, sardine), and can also be found in squid and cuttlefish. In contrast, they are absent from fish in waters of low salinity, due to the physiological requirements of euphausiids, which are needed to complete their life cycle. Anisakids are also uncommon in areas where cetaceans are rare, such as the southern North Sea.^[17]

Similar parasites

Cod or seal worm Pseudoterranova (Phocanema, Terranova) decipiens
Contracaecum spp.
Hysterothylacium (Thynnascaris) spp.

References

^ Berger SA, Marr JS. Human Parasitic Diseases Sourcebook. Jones and Bartlett Publishers: Sudbury, Massachusetts, 2006.
^ Dujardin F. 1845. Histoire naturelle des helminthes ou vers intestinaux. xvi, 654+15 pp. (Anisakis: page 220)
^ Mattiucci, S.; Nascetti, G. (2006). "Molecular systematics, phylogeny and ecology of anisakid nematodes of the genus Anisakis Dujardin, 1845: an update". Parasite 13 (2): 99–113. doi:10.1051/parasite/2006132099. ISSN 1252-607X. PMID 16800118.
^ Amato Neto V, Amato JG, Amato VS (2007). "Probable recognition of human anisakiasis in Brazil". Rev. Inst. Med. Trop. Sao Paulo 49 (4): 261–2. doi:10.1590/s0036-46652007000400013. PMID 17823758.
^ WaiSays: About Consuming Raw Fish Retrieved on April 14, 2009
^ For Chlonorchiasis: Public Health Agency of Canada > Clonorchis sinensis - Material Safety Data Sheets (MSDS) Retrieved on April 14, 2009
^ For Anisakiasis: WrongDiagnosis: Symptoms of Anisakiasis Retrieved on April 14, 2009
^ For Diphyllobothrium: MedlinePlus > Diphyllobothriasis Updated by: Arnold L. Lentnek, MD. Retrieved on April 14, 2009
^ For symptoms of diphyllobothrium due to vitamin B12-deficiency University of Maryland Medical Center > Megaloblastic (Pernicious) Anemia Retrieved on April 14, 2009
^ ^a ^b ^c Audicana, Maria Teresa; Kennedy, MW (2008). "Anisakis Simplex: From Obscure Infectious Worm to Inducer of Immune Hypersensitivity". Clinical Microbiology Reviews 21 (2): 360–379. doi:10.1128/CMR.00012-07. PMC 2292572. PMID 18400801.
^ ^a ^b [1] Bad Bug Book: Foodborne Pathogens Microorganisms and Natural Toxins Handbook. Food and Drug Administration.
^ John, David T.; William Petri (2006). Markell and Voge's Medical Parasitology. St. Louis: Saunders. pp. 267–270. ISBN 0-7216-7634-0.
^ Nieuwenhuizen, N; Lopata, AL; Jeebhay, MF; Herbert, DR; Robins, TG; Brombacher, F (2006). "Exposure to the Fish Parasite Anisakis Causes Allergic Airway Hyperreactivity and Dermatitis". The Journal of allergy and clinical immunology 117 (5): 1098–105. doi:10.1016/j.jaci.2005.12.1357. PMID 16675338.
^ Nakaji K (2009). "Enteric anisakiasis which improved with conservative treatment". Intern. Med. 48 (7): 573. doi:10.2169/internalmedicine.48.1905. PMID 19336962.
^ Sugita S, Sasaki A, Shiraishi N, Kitano S (April 2008). "Laparoscopic treatment for a case of ileal anisakiasis". Surg Laparosc Endosc Percutan Tech 18 (2): 216–8. doi:10.1097/SLE.0b013e318166145c. PMID 18427347.
^ Pacios, Enrique; Arias‐diaz, Javier; Zuloaga, Jaime; Gonzalez‐armengol, Juan; Villarroel, Pedro; Balibrea, Jose L. (2005). "Albendazole for the Treatment of Anisakiasis Ileus". Clinical Infectious Diseases 41 (12): 1825–6. doi:10.1086/498309. PMID 16288416.
^ Grabda, J. (1976). "Studies on the life cycle and morphogenesis of Anisakis simplex (Rudolphi, 1809)(Nematoda: Anisakidae) cultured in vitro". Acta Ichthyologica et Piscatoria 6 (1): 119–131.

External links

CDC page on Anisakiasis
Endoscopy video of Anisakiasis
Sushi, nemotodes and allergies in Canada

UpToDate Contents

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1. その他の線虫 miscellaneous nematodes
2. 海産物アレルギー：魚介類 seafood allergies fish and shellfish
3. 小児および成人におけるアナフィラキシーの鑑別診断 differential diagnosis of anaphylaxis in children and adults
4. 新規発症の蕁麻疹 new onset urticaria
5. 肉芽腫性胃炎 granulomatous gastritis

English Journal

Fishing area and fish size as risk factors of Anisakis infection in sardines (Sardina pilchardus) from Iberian waters, southwestern Europe.

Molina-Fernández D1, Malagón D1, Gómez-Mateos M1, Benítez R1, Martín-Sánchez J1, Adroher FJ2.
International journal of food microbiology.Int J Food Microbiol.2015 Jun 16;203:27-34. doi: 10.1016/j.ijfoodmicro.2015.02.024. Epub 2015 Feb 28.
The sardine (Sardina pilchardus) is a fish commonly consumed and appreciated in many countries, although they are more likely to be eaten fresh in western Mediterranean countries such as Spain, Portugal, France or Italy. A molecular epidemiological survey of sardines from 5 fishing areas of the Span
PMID 25770431

Sonographic diagnosis of intestinal anisakiasis presenting as small bowel obstruction.

Ogata M1, Tamura S, Matsunoya M.
Journal of clinical ultrasound : JCU.J Clin Ultrasound.2015 Jun;43(5):283-7. doi: 10.1002/jcu.22194. Epub 2014 Jun 25.
BACKGROUND: To evaluate the accuracy of ultrasonography (US) in the diagnosis of intestinal anisakiasis presenting as small bowel obstruction.METHODS: We retrospectively reviewed the clinical features, US examinations, and CT scans of seven patients with intestinal anisakiasis presenting as small bo
PMID 24962268

Morbidity and mortality in stranded Cook Inlet beluga whales Delphinapterus leucas.

Burek-Huntington KA1, Dushane JL, Goertz CE, Measures LN, Romero CH, Raverty SA.
Diseases of aquatic organisms.Dis Aquat Organ.2015 May 11;114(1):45-60. doi: 10.3354/dao02839.
The endangered Cook Inlet (Alaska, USA) stock of beluga whales Delphinapterus leucas declined 47% between 1994 and 1998, from an estimated 653 whales to 347 whales, with a continued decline to approximately 312 in 2012. Between 1998 and 2013, 164 known dead strandings were reported by the National M
PMID 25958805

Japanese Journal

生食用サンマ加工食品からのアニサキス幼虫の検出

小川和夫,巖城隆,荒木潤 [他],伊藤直樹
日本水産學會誌 = Bulletin of the Japanese Society of Scientific Fisheries 78(6), 1193-1195, 2012-11-15
NAID 10031125885

イカ摂取により発症したと考えたアニサキスアレルギーの1例 : Ani s 1, 2および12ならびにトロポニンCの陽性例

飯島茂子,森山達哉,市川秀隆 [他],小林征洋,塩見一雄
アレルギー 61(8), 1104-1110, 2012-08-30
症例は62歳男性.過去に3回,サンマ,カツオ,イワシにてアレルギー症状を起こしたことがある.今回,イカ摂取により発症したと考えたアニサキスアレルギーの1例を報告する.イクラとサーモンの和え物,サバの焼き魚を摂取して1時間後にマグロ,イカの刺身を摂取したところ,直後に,膨疹,意識消失,血圧低下が出現した.種々の海産物等でのImmunoCAP(特異的IgE測定)およびプリックテストはすべて陰性であった …
NAID 110009495642

ダブルバルーン小腸内視鏡検査が診断に有用であった小腸アニサキス症の1例

池辺美奈子,松田充,平井聡,堀田洋介,島谷明義,松田耕一郎,平松活志,荻野英朗,野田八嗣
日本消化器内視鏡学会雑誌 = Gastroenterological endoscopy 54(8), 2246-2251, 2012-08-20
症例は54歳男性．刺身摂取後約1週間で腹痛増強しイレウス状態にて当科入院となった．腹部造影CTでは，小腸イレウスの所見で，回腸に限局性壁肥厚と異常濃染を認めた．翌日にイレウスは解除し，第8病日に施行した経肛門的小腸ダブルバルーン内視鏡検査（DBE）にて回盲弁から約1m口側に約半周性の発赤を伴った腫瘤性病変を認めた．同部位の生検にて著明な脱顆粒を伴う好酸球浸潤とCharcot-Leyden crys …
NAID 10031122059

Related Pictures

★リンクテーブル★

リンク元	「アニサキス症」「アニサキス属」「アニサキス」

「アニサキス症」

Anisakis
Classification and external resources
Specialty	Infectious disease
ICD-10	B81.0
ICD-9-CM	127.1
DiseasesDB	32147
Patient UK	Anisakis
MeSH	D017129
	[edit on Wikidata]

Anisakis
	Anisakis simplex
Scientific classification
Kingdom:	Animalia
Phylum:	Nematoda
Class:	Secernentea
Order:	Ascaridida
Family:	Anisakidae
Genus:	Anisakis; Dujardin, 1845
Species
	A. pegreffii; A. physeteris; A. schupakovi; A. simplex (Rudolphi, 1809) Dujardin, 1845; A. typica; A. ziphidarum;

　　[★]

英: anisakiasis
関: アニサキス Anisakis、アニサキスIgG・IgA抗体

分類

穿入部位は胃が90%以上、腸管は5-8%

病態

虫体刺入によるI型、III型アレルギーが関与している、らしい。

病理

虫体刺入部位の粘膜には好酸球が浸潤し肉芽腫を形成。末梢血の好酸球は増加しない。

予防

加熱処理により幼虫は死亡する

参考

1

http://www.travel-med.bug4all.jp/zoology/parasites/nematoda/anisakis.html

2

http://www.pref.aichi.jp/eiseiken/5f/anisakiasis.html

. [charged] Miscellaneous nematodes - uptodate [1]

「アニサキス属」

　　[★]

英: Anisakis

参考

wikipedia ja

http://ja.wikipedia.org/wiki/%E3%82%A2%E3%83%8B%E3%82%B5%E3%82%AD%E3%82%B9

「アニサキス」

　　[★]

英: Anisakis
関: アニサキス属、アニサキス症、胃アニサキス症

[1] Berger SA, Marr JS. Human Parasitic Diseases Sourcebook. Jones and Bartlett Publishers: Sudbury, Massachusetts, 2006.

[2] Dujardin F. 1845. Histoire naturelle des helminthes ou vers intestinaux. xvi, 654+15 pp. (Anisakis: page 220)

[MattiucciNascetti2006-3] Mattiucci, S.; Nascetti, G. (2006). "Molecular systematics, phylogeny and ecology of anisakid nematodes of the genus Anisakis Dujardin, 1845: an update". Parasite 13 (2): 99–113. doi:10.1051/parasite/2006132099. ISSN 1252-607X. PMID 16800118.

[pmid17823758-4] Amato Neto V, Amato JG, Amato VS (2007). "Probable recognition of human anisakiasis in Brazil". Rev. Inst. Med. Trop. Sao Paulo 49 (4): 261–2. doi:10.1590/s0036-46652007000400013. PMID 17823758.

[wai-5] WaiSays: About Consuming Raw Fish Retrieved on April 14, 2009

[6] For Chlonorchiasis: Public Health Agency of Canada > Clonorchis sinensis - Material Safety Data Sheets (MSDS) Retrieved on April 14, 2009

[7] For Anisakiasis: WrongDiagnosis: Symptoms of Anisakiasis Retrieved on April 14, 2009

[8] For Diphyllobothrium: MedlinePlus > Diphyllobothriasis Updated by: Arnold L. Lentnek, MD. Retrieved on April 14, 2009

[9] For symptoms of diphyllobothrium due to vitamin B12-deficiency University of Maryland Medical Center > Megaloblastic (Pernicious) Anemia Retrieved on April 14, 2009

[Audicana-10] Audicana, Maria Teresa; Kennedy, MW (2008). "Anisakis Simplex: From Obscure Infectious Worm to Inducer of Immune Hypersensitivity". Clinical Microbiology Reviews 21 (2): 360–379. doi:10.1128/CMR.00012-07. PMC 2292572. PMID 18400801.

[FDA-11] [1] Bad Bug Book: Foodborne Pathogens Microorganisms and Natural Toxins Handbook. Food and Drug Administration.

[John-12] John, David T.; William Petri (2006). Markell and Voge's Medical Parasitology. St. Louis: Saunders. pp. 267–270. ISBN 0-7216-7634-0.

[Nieuwenhuizen-13] Nieuwenhuizen, N; Lopata, AL; Jeebhay, MF; Herbert, DR; Robins, TG; Brombacher, F (2006). "Exposure to the Fish Parasite Anisakis Causes Allergic Airway Hyperreactivity and Dermatitis". The Journal of allergy and clinical immunology 117 (5): 1098–105. doi:10.1016/j.jaci.2005.12.1357. PMID 16675338.

[pmid19336962-14] Nakaji K (2009). "Enteric anisakiasis which improved with conservative treatment". Intern. Med. 48 (7): 573. doi:10.2169/internalmedicine.48.1905. PMID 19336962.

[pmid18427347-15] Sugita S, Sasaki A, Shiraishi N, Kitano S (April 2008). "Laparoscopic treatment for a case of ileal anisakiasis". Surg Laparosc Endosc Percutan Tech 18 (2): 216–8. doi:10.1097/SLE.0b013e318166145c. PMID 18427347.

[16] Pacios, Enrique; Arias‐diaz, Javier; Zuloaga, Jaime; Gonzalez‐armengol, Juan; Villarroel, Pedro; Balibrea, Jose L. (2005). "Albendazole for the Treatment of Anisakiasis Ileus". Clinical Infectious Diseases 41 (12): 1825–6. doi:10.1086/498309. PMID 16288416.

[17] Grabda, J. (1976). "Studies on the life cycle and morphogenesis of Anisakis simplex (Rudolphi, 1809)(Nematoda: Anisakidae) cultured in vitro". Acta Ichthyologica et Piscatoria 6 (1): 119–131.

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案内

Anisakis