Pseudoterranova Mozgovoi, 1951
analyses by Nadler et al (2005) demonstrated strong support for the
monophyly of Pseudoterranova, Phocasacaris,
Contracaecum and Anisakis
in the family
Humans are accidental hosts due to ingestion of raw or undercooked fish
containing the third infective-stage larvae. Human anisakiasis patients
suffer from abdominal pain, nausea, vomiting, and/or diarrhea (Dorny et al.,
The following detailed descriptions and lifecycles of nematodes
associased with Anisakiasis are provided courtesy of CDC, the Centers for
Disease Control and Prevention
Anisakiasis is caused by the ingestion of larvae of several species of
ascaridoid nematodes (roundworms), which are sometimes called herringworm, codworm, sealwormÂ, in undercooked marine fish. Known human-infecting
anisakid species include members of the Anisakis
simplex complex [A.
simplex sensu stricto, A.
pegreffii, A. berlandi (=A.
simplex C)], the Pseudoterranova
decipiens complex (P.
decipiens sensu stricto, P.
azarasi, P. cattani, and others), and the Contracecum
osculatum complex. Recent genetic studies
have revealed high diversity within these anisakid groups, suggesting
additional cryptic species are likely represented in zoonotic infections.
Adult stages of anisakid nematodes reside in the stomach of marine mammals,
where they are embedded in the mucosa in clusters. Unembryonated eggs
produced by adult females are passed in the feces of marine mammals .
The eggs become embryonated in water, undergoing two developmental molts ,
and hatch from the eggs as free-swimming ensheathed third-stage (L3) larvae .
These free-swimming larvae are then ingested by crustaceans .
The ingested larvae grow within the crustacean hemocoel, and become
infective to fish and cephalopod paratenic hosts. After preying upon
infected crustaceans, the digested L3 larvae migrate from the paratenic host
intestine into the abdominal cavity, and eventually to the tissues of the
mesenteries and skeletal muscle. Through predation, tissue-stage L3 larvae
can be transmitted among paratenic hosts .
Fish and squid maintain L3 larvae that are infective to humans and marine
When fish or squid containing third-stage larvae are ingested by definitive
host marine mammals, the larvae molt twice and develop into adult worms .
After ingestion by humans, the anisakid larvae penetrate the gastric and
intestinal mucosa, causing the symptoms of anisakiasis .
Dorny, P., Praet, N., Deckers, N. and Gabriel, S. 2009. Emerging food-borne
parasites. Veterinary Parasitology 163:196-206.
Klimpel, S. and Palm, H. W. 2011. Anisakid nematode (Ascaridoidea) life
cycles and distribution: Increasing zoonotic potential in the time of
climate change? In Mehlhorn, H. (Ed.), Progress in parasitology.
Parasitology research monographs, Vol. 2 Springer, Berlin, pp. 201-222.
Nadler, S.A., D'Amelio, S., Dailey, M.D. Paggi, L., Siu, S., Sakinari, J.
A. Molecular phylogenetics abnd diagnosis of Anisakis, Pseudoterranova, and
Pseudoterranova from Nothern Pacific marine mammals. J. Parasitol.