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Treatment[edit]
Standard intravenous preparations of potassium phosphate are available and are routinely used in malnourished people and people who consume excessive amounts of alcohol. Supplementation by mouth is also useful where no intravenous treatment are available. Historically one of the first demonstrations of ... | null |
Anisakis
Anisakis simplex
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Anisakidae
Genus: Anisakis
Dujardin, 1845
Species
A. berlandi
A. brevispiculata
A. nascettii
A. oceanica
A. paggiae
A. pegreffii
A. physeteris
A. schupakovi
A. similis
A.... | null |
Etymology[edit]
The genus Anisakis was defined in 1845[2] by Félix Dujardin as a subgenus of the genus Ascaris Linnaeus, 1758. Dujardin did not make 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 Ani... | null |
Life cycle[edit] Complex life cycle of Anisakis worms Anisakis species have complex life cycles which pass through several hosts through the course of their lives. Eggs hatch in seawater, and larvae are eaten by crustaceans, usually euphausids. The infected crustaceans are subsequently eaten by fish or squid, and the n... | null |
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 can infect humans who eat raw or undercooked fish.[citation needed] | null |
Reproduction[edit]
Sexual reproduction occurs once the larvae have reached a definitive host and completed their final molt, at which point sexual organs are developed.[3] Females are capable of producing 2.6 million eggs, depending on species and size at sexual maturity.[4]
The known diversity of the genus has increas... | null |
Morphology[edit] A scanning electron micrograph of the mouthparts of A. simplex Anisakis 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 projectio... | null |
When in the final host, anisakids are longer, thicker, and more sturdy, to deal with the hazardous environment of a mammalian gut.[citation needed] | null |
Health implications[edit]
It has been suggested that this section be split out into another article titled Anisakiasis. (Discuss) (January 2024)
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 wo... | null |
Anisakiasis[edit] Anisakiasis Differential symptoms of parasite infection by raw fish: Clonorchis sinensis (trematode/fluke), Anisakis (nematode/roundworm) and Diphyllobothrium (cestode/tapeworm),[7] all have gastrointestinal, but otherwise distinct, symptoms.[8][9][10][11] Specialty Infectious disease Anisakiasis is a... | null |
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.[12][13] Anisakiasis may present as a gastric, intestinal, or allergic disease.[14] The first case of human infection by a me... | null |
The areas of highest prevalence are Scandinavia (from cod livers), Japan (after eating sashimi), the Netherlands (by eating infected fermented herrings (maatjes), Spain (from eating anchovies and other fish marinated in escabeche), and along the Pacific coast of South America (from eating ceviche). The frequency in the... | null |
In Japan, more than 1,000 cases are reported annually.[16] Development of better diagnostic tools and greater awareness has led to more frequent reporting of anisakiasis. | null |
Diagnosis[edit]
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.[citation needed]
Important clues for the diagnosis of anisakiasis include a recent history of eating raw or ... | null |
Prevention[edit] 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[citation needed] or freezing. The FDA recommends all shellfish and fish inten... | null |
[citation needed] 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 in the Netherlands.[19] The best preventive measure for Anisiakis is to avoid... | null |
Treatment[edit]
For the worm, humans are a dead-end host. Anisakis and Pseudoterranova larvae cannot survive in humans, and eventually die. In some cases, the infection resolves with only symptomatic treatment.[22] In other cases, however, the infection can lead to small bowel obstruction, which may require surgery,[23... | null |
Allergic reactions[edit] 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 many biochemicals into the surrounding tissues when they infect a fish. They are... | null |
The frequency of allergic symptoms in connection with fish ingestion has led to the concept of gastroallergic anisakiasis, an acute IgE-mediated generalized reaction.[15] Occupational allergy, including asthma, conjunctivitis, and contact dermatitis, has been observed in fish processing workers.[25] sensitization and a... | null |
Occurrence[edit] Anisakid larvae in the body cavity of a mackerel (Scomber scombrus) 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 requi... | null |
Anisakids are also uncommon in areas where cetaceans are rare, such as the southern North Sea.[27] Due to having complex life cycles, species-specific relationships and their eggs being released in the feces of their definitive host, the identification of anisakids in local fish populations can be a useful tool in asse... | null |
Taxonomy[edit]
There are currently 13 species known to exist in this genus, with 12 formally described and one additional species given a temporary name (A. simplex sensu Davey, 1971 is a temporary name). There are three additional species classified as taxon inquirendum (A. dussumierii (Brenden, 1870), A. insignis (Di... | null |
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