Rev: 10/19/2026
Chromadorea
Chromadoria
Rhabditida
Spirurina
Ascaridoidea
Anisakidae
Porrocaecum Railliet & Henry, 1912
Type species of the genus: Porrocaecum crassum (Deslongchamps, 1824) Railliet & Henry, 1912
Although sometimes classified in the family Heterocheilidae, molecular analyses by Nadler et al (2005) demonstrated strong support for the monophyly of Contracaecum, Phocasacaris, Porrocaecum, Pseudoterranova and Anisakis in the family Anisakidae.
Synonyms:
Ref: Flagerholm and Overstreet, 2008
The genus Porrocaecum includes species distributed globally in marine environments (Shamsi et al., 2009), usually associated with waterbirds.
Food Sources and Feeding strategies for the genus Porrocaecum
Parasites the digestive system of fish-eating birds.
Adult Porrocaecum spp. are parasites of fish-eating birds and marine mammals, including both cetaceans and pinnipeds. Typically they are parasites of the proventriculus, gizzard, and intestines of birds, seals, and dolphins.
Usually, the second larval stage of Porrocaecum spp. hatches from eggs released in the feces from infected definitve hosts. Copepods act as intermediate hosts, and small fish harboring third stage larvae act as vertebrate intermediate or paratenic hosts
Thiird-stage (L3) larvae he second larval stage of Porrocaecum spp. hatch from fully embyronated eggs that are passed in the feces of their avian definitive hosts. These are ingested by a crustacean (copepod) intermediate host and penetrate into their body cavity. Small fish harboring third stage larvae act as vertebrate intermediate or paratenic hosts when they ingest infected crustaceans. The L3 larvae encyst within the intestinal wall, mesentery, liver, or other internal organs of paratenic fish hosts, but are not known enter muscle tissue. When crustaceans or fish are ingested by a suitable avian host, the L3 larvae undergo final molts to fourth-stage (L4) larvae and adults within the proventriculus of the avian host.
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., 2009).
The following detailed descriptions and lifecycles of nematodes associated with Anisakiasis are provided courtesy of CDC, the Centers for Disease Control and Prevention
Causal Agents
Anisakiasis is caused by the ingestion of larvae of several species of ascaridoid nematodes (roundworms), which are sometimes called herringworm, codworm, sealworm, 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 mammals .
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 .
Unmanageable infections in wild birds result from biological and environmental conditions that concentrate birds and intermediate hosts together.
In domestic situations, intermediate and paratenic hosts can be eliminated or reduced. Birds can be medicated, if necessary, for treatment of breeding stock or valuable individuals.
Albendazole and fenbendazole were effective against Contracaecum multipapillatum in the Brown Pelican while piperazine dihydrochloride, clorsulon, and Curatrem were not. Recent studies should be reviewed in this area with regards to both efficacy and safety.
Cooking-infected products destined for consumption by humans or other animals will kill all stages of Contracaecum and Porrocaecum,
The US Department of Agriculture recommends freezing and storing at -20 C or below for 7 days. Heating to 63 C for 17 min will also kill all nematodes in infected tissue, as well as bacteria.
Control practices for some anisakid infections under normal conditions in the wild can be cost-prohibitive, not practical, or totally unnecessary.
For Porrocaecum or Contracaecum, control strategies should first consider eliminating or reducing access to the intermediate hosts.
Ref: Fagerholm H-P. and Overstreet, R.M. 2008
Dorny, P., Praet, N., Deckers, N. and Gabriel, S. 2009. Emerging food-borne parasites. Veterinary Parasitology 163:196-206.
Fagerholm H-P. and Overstreet, R.M. 2008. Ascaridoid Nematodes: Contracaecum, Porrocaecum, and Baylisascaris, Chapter 24 in Atkinson, C.T., Thomas, N.J. and Hunter, D.B. (eds) Parasitic Diseases of Wild Birds. John Wiley & Sons, Inc. ISBN: 978-0-813-82081-1
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 and diagnosis of Anisakis, Pseudoterranova, and Contracaecum from Nothern Pacific marine mammals. J. Parasitol. 91:1413-1429.
Shamsi, S., Norman, R., Gasser, R., Beveridge, I. 2009. Redescription and genetic characterization of selected Contracaecum spp. (Nematoda: Anisakidae) from various hosts in Australia. Parasitology Research 104:1507-1525.