海獸胃線蟲
维基百科，自由的百科全书
| 海獸胃線蟲 | ||||||||||||||
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| Image:4-S05A 010.jpg 單線蟲(Anisakis simplex) |
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| Anisakis (Karl Rudolphi 1809) |
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海獸胃線蟲，又名異尖線蟲是屬於線蟲的一種寄生蟲，通體白色，一端略顯暗沉，其生命的循環透過魚類和海洋中的哺乳動物來完成，雖然不能利用人類發育成熟而完成生命週期，但是誤食還有幼蟲、未經煮熟的魚肉，可使用餐者受到感染，而患者則會出現劇烈的腹痛或過敏等反應。
目录 |
[编辑] 生命週期
線蟲種有複雜的生命周期途經多個主機通過其人生歷程. 幼蟲及卵孵化海水甲殼是吃了,通常euphausids. 隨後是吃了感染的甲殼魚及魷魚或線蟲腸道壁進入洞穴和encysts了防護外套, 通常在外面的內臟器官,但偶爾在下方皮膚或肌肉. 生命周期結束時,魚是吃了感染了一種海洋哺乳動物、 如鯨魚或海豚. excysts在腸道的線蟲、飼料、坑、交配、產卵發佈入海水主持人大便. 作為一個海洋哺乳動物的腸道功能非常相似,是人,線蟲許可證. 能夠感染人體吃生魚或者未徹底. 屬多元化大大增強,過去20年, 隨著現代技術的物種基因鑒定. 據發現,每個物種最終東道主自己家裡兄弟姊妹種生化及基因識別線蟲許可證. 、 這是繁殖孤立. 這項發現使得姊妹種不同比例魚用來作為反映居民身份魚類
[编辑] 形態
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 located anteriorly, and surrounded by projections used in feeding and sensation, with the anus slightly offset from the posterior. The epidermis secretes a layered cuticle that protects 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 stage of life cycle which it is in. In the stage which infects fish, Anisakis 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.
[编辑] 健康影響
Anisakids pose a risk to human health in two ways: through infection with worms from the eating of under-processed fish, and through allergic reactions to chemicals left by the worms in fish flesh.
[编辑] 異尖線蟲病
Anisakiasis is the disease caused by infection with Anisakis worms. 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). Heating to 60 °C, or freezing to below −20 °C is an effective method of killing Anisakis.
Within hours after ingestion of infective larvae, violent abdominal pain, nausea, and vomiting may occur. Occasionally the larvae are coughed up. If the larvae pass into the bowel, a severe eosinophilic granulomatous response may also occur 1 to 2 weeks following infection, causing symptoms mimicking Crohn's disease.
Diagnosis can be made by gastroscopic examination during which the 2 cm larvae are visualized and removed, or by histopathologic examination of tissue removed at biopsy or during surgery.
Humans are thought to be more at risk of Anisakiasis from eating wild fish than farm-raised fish, because the grinding process used for pellet food for farmed fish kills the parasites. A 2003 study by the Food and Agriculture Organization of the United Nations found no parasites in any farm-raised salmon, in contrast to wild salmon in which parasites were frequently found[來源請求].
Many countries requires all types of fish with potential risk intended for raw consumption to be previously frozen to kill parasites.
[编辑] 過敏反應
Even when throroughly cooked Anisakis pose a health risk to humans. Anisakids (and related species such as the sealworm, Pseudoterranova spp., 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.
People who are sensitized to nematodes can have severe anaphylactic reactions after eating fish which have been infected with Anisakis spp. This is often confused with a fish or shellfish allergy, as the allergenic components of Anisakids are difficult to test for and are often produce a reaction in tests for other allergens.
[编辑] 治療
For the worm, humans are a dead-end host. Anisakis and Pseudoterra larvae cannot survive in humans and eventually die. Treatment therefore in the vast majority of cases is symptomatic, with a heavy dose of re-assurance. The only indication for treatment is small bowel obstruction due to Anisakis larvae, which may require emergency surgery, although there are case reports of treatment with albendazole alone (avoiding surgery) being successful (Pacios et al., 2005).
[编辑] 出現
Larval anisakis are common parasites of marine and anadromous fish, 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 Euphausids, which are needed to complete their life cycle. Anisakids are also uncommon in areas where cetaceans are rare, such as the southern North Sea (Grabda, 1976).
[编辑] 形態
[编辑] 生活史
[编辑] 流行病學
[编辑] 臨床表現
[编辑] 参考文献
- Akbar A, Ghosh H (2005). "Anisakiasis—a neglected diagnosis in the West". Allergy 37 (1): 7–9.
- 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.
- Lorenzo S, Iglesias R, Leiro J, Ubeira FM, Ansotegui I, Garcia M, Fernandez de Corres L (2000). "Usefulness of currently available methods for the diagnosis of Anisakis simplex allergy". Allergy 55: 627–33.
- Mattiucci S., Nascetti G., Tortini E., Ramadori L., Abaunza P. & Paggi L (2000). "Composition and structure of metazoan parasitic communities of European hake (Merluccius merluccius) from Mediterranean and Atlantic waters: stock implications". Parassitologia 42 (S1): 176–186.
- Orecchia P, Paggi L, Mattiucci S, Smith JW, Nascetti G & Bullini L (1986). "Electrophoretic identification of larvae and adults of Anisakis (Ascaridida:Anisakidae)". J Helminthol 60 (4): 331–9.
- Pacios E, Arias-Diaz J, Zuloaga J, Gonzalez-Armengol J, Villarroel P, Balibrea JL (2005). "Albendazole for the treatment of anisakiasis ileus". Clin Infect Dis 41: 1825–6.
