Anisakis simplex

Anisakis simplex
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Nematoda
Class: Chromadorea
Order: Rhabditida
Family: Anisakidae
Genus: Anisakis
Species:
A. simplex
Binomial name
Anisakis simplex
(Rudolphi, 1809)
Synonyms
  • Ascaris simplex Rudolphi, 1809[1]

Anisakis simplex, known as the herring worm, is a species of nematode in the genus Anisakis. Like other nematodes, it infects and settles in the organs of marine animals, such as salmon, mackerels and squids.[2][3] It is commonly found in cold marine waters, such as the Pacific Ocean and Atlantic Ocean.[4][5]

This species begins as an egg found in the feces of its host, and hatches as a second-stage larva in the ocean, where it survives for several days.[4] This larva is then consumed by an intermediate host, usually a krill, and it develops into a third stage larva within the body of this intermediate host.[4] The krill is then ingested by a predator, such as squid or fish, which act as the paratenic host for A. simplex.[4] The worm reaches the end of its life cycle when the paratenic host is ingested by a whale or another marine mammal.[4] In the abdominal cavity of this final host, A. simplex develops into a fully mature worm and reproduces to form eggs, which are then expelled from the body of the final host.[4]

A. simplex generally possesses digestive and excretory organs, such as an oesophagus and intestine.[6] However, its morphological structure changes as it develops from one life stage to another.[6] When it is fully mature, it has defined lip structures, a regularly patterned outer surface, and fully developed reproductive organs.[6]

The consumption of raw or undercooked seafood, such as sashimi and ceviche, puts humans at risk for developing an infection or allergic reaction caused by A. simplex.[3][5] The worm can infect the stomach or intestine by lodging itself within the walls of the organ and producing digestive enzymes to penetrate mucus layers.[3] It occasionally pierces through the wall completely and travels in the abdominal cavity.[3] Acute symptoms, such as abdominal cramps, nausea and diarrhoea, arise hours after ingestion.[3][7][8] The infection can be chronic if not treated. Treatment involves removal of the worm by endoscopy or surgery.[7]

  1. ^ Rudolphi, Carolo Asmundo (1809). "Ascaris simplex R.". Animadversiones in generaet species entozoorum. Entozoorum, sive vermium intestinalium: Historia naturalis. 2. Amstelaedami: Taberna Libraria et Artium. p. 170.
  2. ^ Cite error: The named reference Gang & Hallem, 2016 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference Audicana et al., 2003 was invoked but never defined (see the help page).
  4. ^ a b c d e f Cite error: The named reference Nagasawa, 1990 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Ritter, 2001 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Ishii et al., 1989 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference CDC, 2019 was invoked but never defined (see the help page).
  8. ^ Pravettoni, V., Primavesi, L., & Piantanida, M. (2012). Anisakis simplex: current knowledge. European Annals of Allergy and Clinical Immunology, 44(4), 150–156.