Summary: Infection of humans with the nematode worm parasite Anisakis simplex was first described in the 1960s in association with the consumption of raw or undercooked fish During the 1990s it was realized that even the ingestion of dead worms in food fish can cause severe hypersensitivity reactions, that these may be more prevalent than infection itself, and that this outcome could be associated with food preparations previously considered safe Not only may allergic symptoms arise from infection by the parasites (“gastroallergic anisakiasis”), but true anaphylactic reactions can also occur following exposure to allergens from dead worms by food-borne, airborne, or skin contact routes This review discusses A simplex pathogenesis in humans, covering immune hypersensitivity reactions both in the context of a living infection and in terms of exposure to its allergens by other routes Over the last 20 years, several studies have concentrated on A simplex antigen characterization and innate as well as adaptive immune response to this parasite Molecular characterization of Anisakis allergens and isolation of their encoding cDNAs is now an active field of research that should provide improved diagnostic tools in addition to tools with which to enhance our understanding of pathogenesis and controversial aspects of A simplex allergy We also discuss the potential relevance of parasite products such as allergens, proteinases, and proteinase inhibitors and the activation of basophils, eosinophils, and mast cells in the induction of A simplex-related immune hypersensitivity states induced by exposure to the parasite, dead or alive

Anisakis simplex: from Obscure Infectious Worm to Inducer of Immune Hypersensitivity

Advances in the taxonomy and ecological aspects concerning geographical distribution and hosts of the so far genetically recognised nine taxa of the nematodes belonging to genus Anisakis (i.e. A. pegreffii, A. simplex s.s., A. simplex C, A. typica, A. ziphidarum, Anisakis sp., A. physeteris, A. brevispiculata and A. paggiae) are here summarized. Genetic differentiation and phylogenetic relationships inferred from allozyme (20 enzyme-loci) and mitochondrial (sequences of cox-2 gene) markers, are revised and compared. The two genetic analyses are congruent in depicting their phylogenetic relationships. Two main clusters are showed to exist in the obtained trees, one encompassing the species A. pegreffii, A. simplex s.s., A. simplex C, A. typica, A. ziphidarum and Anisakis sp.; while, the second including A. physeteris, A. brevispiculata and A. paggiae. The existence of two clades is also supported by their morphological differentiation in adult and larval morphology. Comparison of phylogenetic relationships among Anisakis spp. with those currently available for their cetacean definitive hosts suggests parallelism between host and parasite phylogenetic tree topologies. Preliminary data for reconstruction of a possible co-evolutionary scenario between cetacean hosts and their Anisakis endoparasites suggests that cospeciation and host-switching events may have accompanied the evolution of this group of parasites. Finally, genetic/molecular markers for the identification of the so far genetically recognized taxa of Anisakis at any life-stage and both sexes were given also in relation to human anisakiosis is discussed.

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Molecular systematics, phylogeny and ecology of anisakid nematodes of the genus Anisakis dujardin, 1845 : An update

This review addresses the biodiversity, biology, distribution, ecology, epidemiology, and consumer health significance of the so far known species of Anisakis, both in their natural hosts and in human accidental host populations, worldwide. These key aspects of the Anisakis species' biology are highlighted, since we consider them as main driving forces behind which most of the research in this field has been carried out over the past decade. From a public health perspective, the human disease caused by Anisakis species (anisakiasis) appears to be considerably underreported and underestimated in many countries or regions around the globe. Indeed, when considering the importance of marine fish species as part of the everyday diet in many coastal communities around the globe, there still exist significant knowledge gaps as to local epidemiological and ecological drivers of the transmission of Anisakis spp. to humans. We further identify some key knowledge gaps related to Anisakis species epidemiology in both natural and accidental hosts, to be filled in light of new 'omic' technologies yet to be fully developed. Moreover, we suggest that future Anisakis research takes a 'holistic' approach by integrating genetic, ecological, immunobiological, and environmental factors, thus allowing proper assessment of the epidemiology of Anisakis spp. in their natural hosts, in human populations, and in the marine ecosystem, in both space and time.

Molecular Epidemiology of Anisakis and Anisakiasis: An Ecological and Evolutionary Road Map.

Anisakiasis is an important fish-borne zoonosis provoked by larval stages of nematodes belonging to the genus Anisakis. The detection and identification of human infections is difficult. This is due to: a) the low specificity of the clinical features and symptomatology related to human infections; b) the paucity of diagnostic features of larvae found in granulomatous lesions characteristic of "invasive anisakiasis"; and c) the lack morphological characters diagnostic at the specific level when larvae of Anisakis are detected. Thus, molecular-based diagnostic approaches are warranted. We have developed a PCR method that amplifies the DNA of Anisakis spp. in fixed paraffin-embedded tissues. This method was applied to a granuloma removed from a human case of intestinal anisakiasis in Italy. Specific primers of the mtDNA cox2 gene were used and sequence analysis was performed according to the procedures already established for species of Anisakis. The sequence obtained (629 bp) was compared with those of the other species of Anisakis which have so far been genetically characterized and with sequences obtained from larval stages of Anisakis collected from the Mediterranean fish Engraulis encrasicolus. This enabled the genetic identification of the larva in the human tissue as A. pegreffii. This is the first instance of human intestinal anisakiasis diagnosed using PCR of DNA purified from a fixed eosinophilic granuloma embedded in paraffin. The case of human anisakiasis presented reinforces the pathological significance of the species A. pegreffii to humans. The molecular/genetic methodological approach based on mtDNA cox2 sequence analysis, described here, can allow easy and rapid identification of Anisakis spp. in formalin-fixed and paraffin embedded tissues removed from cases of either gastric or intestinal human anisakiasis.

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First molecular identification of the zoonotic parasite Anisakis pegreffii(Nematoda: Anisakidae) in a paraffin-embedded granuloma taken from a case of human intestinal anisakiasis in Italy

Effects of anisakid nematodes Anisakis simplex (s.l.), Pseudoterranova decipiens (s.l.) and Contracaecum osculatum (s.l.) on fish and consumer health ☆

A case of intestinal anisakiasis caused by Anisakis sp. larva type I in a woman from Italy who consumed raw marinated anchovies, is reported. The diagnosis was based on the morphological features characteristic of anisakid larval stages, which were readily recognized in a large granuloma removed after emergency surgical treatment.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/666FE3F83AFB1DE5FF3D44B7260279CD/S0022149X04000423a.pdf/div-class-title-intestinal-anisakiasis-in-italy-case-report-div.pdf

Intestinal anisakiasis in Italy: case report.

The ectopic liver (or choristoma) is a rare condition found during autopsy or abdominal exploration for various indications. The authors report two cases of ectopic liver found during laparoscopic cholecystectomy for acute cholestytis. The ectopic liver tissue has been reported to develop in several sites as thoracic cavity, gastrohepatic ligament, adrenal glands, pancreas, esophagus and, above all, gallbladder. The Authors review the literature and report their experience as a contribution to the knowledge of this rare pathological entity.

P. Mingazzini

Papers

Intestinal anisakiasis in Italy: case report.

Ectopic liver nodules: a rare finding during cholecystectomy.