The response of Anisakis simplex (s. s.) to anthelmintics - Specific changes in xenobiotic metabolic processes

Anisakiasis is a parasitic disease transmitted through the consumption of raw or undercooked fish and cephalopods that are infected with larvae of Anisakis simplex (sensu stricto) or Anisakis pegreffii. The purpose of this study was to investigate how A. simplex (s. s.) responds to the influence of anthelmintics such as ivermectin (IVM) and pyrantel (PYR). In vitro experiments were conducted using larvae at two developmental stages of A. simplex (s. s.) (L3 and L4) obtained from Baltic herring (Clupea harengus membras). Larvae were cultured with different concentrations of IVM or PYR (1.56, 3.125, and 6.25 μg/mL) for various durations (3, 6, 9, and 12 h) under anaerobic conditions (37 °C, 5% CO2). The gene expression of actin, ABC transporter, antioxidant enzymes, γ-aminobutyric acid receptors, and nicotinic acetylcholine receptors, as well as the oxidative status were analyzed. The results showed that A. simplex (s. s.) L3 stage had lower mobility when cultured with PYR compared to IVM. The analysis of relative gene expression revealed significant differences in the mRNA level of ABC transporters after treatment with IVM and PYR, compared to the control group. Similar patterns were observed in the gene expression of antioxidant enzymes in response to both drugs. Furthermore, the total antioxidant capacity (TAC) and glutathione S-transferase (GST) activity were higher in the treatment groups than in the control group. These findings suggest a relationship between the expression of the studied genes, including those related to oxidative metabolism, and the effectiveness of the tested drugs.

Increasing intensities of Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878) larvae with weight and sea age in returning adult Atlantic salmon, Salmo salar L., of coastal waters of Norway

Ninety wild Atlantic salmon, Salmo salar L., (1.5-10.3 kg) were caught in the Namsen Fjord near the mouth of River Namsen, mid-Norway, and examined for the presence and distribution of Anisakis simplex (Rudolphi, 1809 det. Krabbe, 1878) larvae by digestion of the viscera and muscles in a pepsin/HCl solution. All salmon were migrating spawners after 1-4 years of feeding in the Atlantic Ocean. All 90 Atlantic salmon had A. simplex larvae in the viscera, and all, except two, had A. simplex larvae in the musculature. The number of A. simplex larvae in each fish varied between 3 and 181, and the total mean number of nematode larvae was 44.5. The intensity of A. simplex larvae was positively correlated with increasing weight and sea age of the host. However, the proportion of larvae in the muscle fillets decreased with increasing host weight and sea age. Atlantic salmon females had more A. simplex larvae than males. In all the fish examined, 70.2% of the A. simplex larvae were found in the viscera and 29.8% in the musculature. The majority (93%) of the larvae in the musculature occurred in the hypaxial sections anterior to the anus. As A. simplex larvae commonly occur in the musculature of wild Atlantic salmon, consumption of unfrozen, raw or semi-raw musculature represents a risk for humans developing anisakiasis.

Shotgun Proteomics for L3 and L4 Anisakis simplex Development Stages

Anisakis simplex s.s. is a parasitic nematode that causes anisakiasis in humans. L3 stage larvae, which are present in many fish species and cephalopods all over the globe, might be consumed and develop occasionally into the L4 stage but cannot reproduce. Anisakiasis is an emerging health problem and economic concern. In recent years, proteomic methods have gained greater acceptance among scientists involved in parasitology and food science. According to that, here, we present tandem mass tag (TMT)-based shotgun proteomics to define differences in proteomic composition between L3 and L4 development stages of A. simplex s.s.

Advances in Omic Studies Drive Discoveries in the Biology of Anisakid Nematodes

Advancements in technologies employed in high-throughput next-generation sequencing (NGS) methods are supporting the spread of studies that, combined with advances in computational biology and bioinformatics, have greatly accelerated discoveries within basic and biomedical research for many parasitic diseases. Here, we review the most updated "omic" studies performed on anisakid nematodes, a family of marine parasites that are causative agents of the fish-borne zoonosis known as anisakiasis or anisakidosis. Few deposited data on Anisakis genomes are so far available, and this still hinders the deep and highly accurate characterization of biological aspects of interest, even as several transcriptomic and proteomic studies are becoming available. These have been aimed at discovering and characterizing molecules specific to peculiar developmental parasitic stages or tissues, as well as transcripts with pathogenic potential as toxins and allergens, with a broad relevance for a better understanding of host-pathogen relationships and for the development of reliable diagnostic tools.

Effectiveness of five flavored Tunisian olive oils on Anisakis larvae type 1: application of cinnamon and rosemary oil in industrial anchovy marinating process

BACKGROUND

Anisakidosis is caused by the ingestion of raw or undercooked fish or cephalopods containing viable Anisakis larvae. Several natural extracts, oils, essential oils, and their compounds have been tested against Anisakis. In this study the effectiveness of Tunisian olive oil with different spices or plants (cardamom, cinnamon, ginger, laurel, and rosemary) was tested against Anisakis larvae type 1.

RESULTS

For the in vitro test, larvae were submerged separately in the oils mentioned above and observed to check viability. Cinnamon oil was the most effective against parasites with lethal time (LT) scores being LT50  = 1.5 days and LT100  = 3 days, followed by rosemary. Laurel, cardamom, and ginger oils were less effective. For the ex vivo experiment, cinnamon, and rosemary oils were tested in anchovy fillets, previously artificially parasitized. Cinnamon was the most effective against parasites (dead after 4 days) as compared to rosemary (7 days).

CONCLUSION

The use of cinnamon and rosemary-flavored olive oil in the industrial marinating process can be considered as an efficient alternative to the freezing process required by European Regulation EC No 853/2004 to devitalize Anisakis. © 2019 Society of Chemical Industry.

Evaluation of different Mediterranean essential oils as prophylactic agents in anisakidosis

CONTEXT

Anisakis Dujardin 1845 (Anisakidae) nematodes can cause gastrointestinal and allergic diseases when humans eat raw or undercooked seafood containing larvae. There is currently no drug available in the market against this parasitic disease, and the study of plant-derived molecules could be useful in the discovery of effective compounds.

OBJECTIVE

This research assesses the biocidal activity of a range of essential oils (EOs) from some Mediterranean plants against larvae found in the musculature of fresh fish.

MATERIALS AND METHODS

EOs composition was analyzed by gas chromatography-mass spectroscopy. All the EOs were diluted at 5% v/v in olive oil to cover the fish with the solutions for 24 h. The larvae that abandoned the muscle and the larvae obtained from the artificial digestion of the fish were collected. Controls were carried out in parallel. Furthermore, Wistar rats were infected with the live larvae collected from the in vitro trials in order to find any larvae that may have penetrated the gastrointestinal wall.

RESULTS

Between 60.8% and 87.6% of parasites treated with EOs abandoned the fish muscle, and the highest in vitro mortality rate was achieved with oregano EO (53.9%). Rats previously treated with oregano, cumin and Spanish lavender EOs showed no detectable lesions in the digestive tract due to the infection with larvae.

CONCLUSIONS

Oregano (Origanum vulgare L. Lamiaceae), cumin (Cuminum cyminum L. Apiaceae) and Spanish lavender (Lavender stoechas L. Lamiaceae) EOs could be used as promising ingredients in the development of products for the control of anisakiasis.

Occurrence of Anisakis (Nematoda: Anisakidae) larvae in unusual hosts in Southern hemisphere

Nematodes belonging to the genus Anisakis are important parasites due to their abundance in seafood and health impacts on humans. In the present study Anisakis larvae were found in a number of uncommon hosts including the Grey petrel, Procellaria cinerea, the Little penguin, Eudyptula minor, Blue-lipped sea krait, Laticauda laticaudata and Spinner shark, Carcharhinus brevipinna. Morphological examination showed nematodes in these animals are Anisakis larval type I. Genetic characterisation suggested that the larva from one Grey petrel was Anisakis berlandi, whereas the other larvae from the second Grey petrel and from the little penguin were Anisakis pegreffii. A number of larvae found in Blue-lipped sea krait and Spinner shark were identified as Anisakis typica. This is the first report of infective stage of Anisakis larvae parasitising hosts other than teleost fish. Understanding of the extent of infection and the pathogenicity of anisakid nematodes in hosts found in the present study is important in the conservation studies and management plans of these hosts.

The Anisakis Transcriptome Provides a Resource for Fundamental and Applied Studies on Allergy-Causing Parasites

Background

Food-borne nematodes of the genus Anisakis are responsible for a wide range of illnesses (= anisakiasis), from self-limiting gastrointestinal forms to severe systemic allergic reactions, which are often misdiagnosed and under-reported. In order to enhance and refine current diagnostic tools for anisakiasis, knowledge of the whole spectrum of parasite molecules transcribed and expressed by this parasite, including those acting as potential allergens, is necessary.

Methodology/Principal Findings

In this study, we employ high-throughput (Illumina) sequencing and bioinformatics to characterise the transcriptomes of two Anisakis species, A. simplex and A. pegreffii, and utilize this resource to compile lists of potential allergens from these parasites. A total of ~65,000,000 reads were generated from cDNA libraries for each species, and assembled into ~34,000 transcripts (= Unigenes); ~18,000 peptides were predicted from each cDNA library and classified based on homology searches, protein motifs and gene ontology and biological pathway mapping. Using comparative analyses with sequence data available in public databases, 36 (A. simplex) and 29 (A. pegreffii) putative allergens were identified, including sequences encoding ‘novel’ Anisakis allergenic proteins (i.e. cyclophilins and ABA-1 domain containing proteins).

Conclusions/Significance

This study represents a first step towards providing the research community with a curated dataset to use as a molecular resource for future investigations of the biology of Anisakis, including molecules putatively acting as allergens, using functional genomics, proteomics and immunological tools. Ultimately, an improved knowledge of the biological functions of these molecules in the parasite, as well as of their immunogenic properties, will assist the development of comprehensive, reliable and robust diagnostic tools.

Nematodes within the genus Anisakis (i.e. A. simplex and A. pegreffii, also known as herring worms) are the causative agents of the fish-borne gastrointestinal illness known as ‘anisakiasis’, with infections resulting in symptoms ranging from mild gastric forms to severe allergic reactions leading to urticaria, gastrointestinal and/or respiratory signs and/or anaphylaxis (‘allergic anisakiasis’). Despite significant advances in knowledge of the pathobiology of allergic anisakiasis, thus far, the exact number and nature of parasite molecules acting as potential allergens are currently unknown; filling this gap is necessary to the development of robust and reliable diagnostics for allergic anisakiasis which, in turn, underpins the implementation of effective therapeutic strategies. Here, we use RNA-Seq and bioinformatics to sequence and annotate the transcriptomes of A. simplex and A. pegreffii, and, as an example application of these resources, mine this data to identify and characterise putative novel parasite allergens based on comparisons with known allergen sequence data from other parasites and other organisms.

Stereo and scanning electron microscopic studies of the third stage larvae of Anisakis simplex

This study was to demonstrate the surface anatomy of the third stage larvae of Anisakis simplex in marine fish using stereo and scanning electron microscopes (SEM). The round worm is slender, elongated and of cylindrically shaped. The head of this worm is a globular structure. The mouth is triangularly shaped and surrounded by three lips. A boring tooth projects dorsally at the anterior end. There are four pairs of tactoreceptors, the labial papillae, enclosing the lips. The tail end is blunt and acquires a distinct slender process, the mucron. Stereomicroscopy revealed the esophagus is elongated, bulbous and club shaped, subdivided into an anterior muscular part and a posterior glandular part or ventriculus. The intestine is a long straight tube where the digestion and absorption occur. Waste pass through the intestine and is stored in the rectum until excreted via the anus. A SEM is a powerful tool in distinguishing worm species, as was seen when examining that the mouth of Anisakis simplex, which is triangular shaped and enclosed by three lips with one boring tooth; other species are different. The mucron projection at the distal end is another distinctive structure revealed by SEM.

Experimental challenge of Anisakis simplex sensu stricto and Anisakis pegreffii (Nematoda: Anisakidae) in rainbow trout and olive flounder

The third-stage larvae of Anisakis simplex sensu lato (s.l.) are found in many marine fishes. To ensure food safety, it is important to determine whether these larvae are present in the body muscle of commercial fish species. However, there is little information regarding the tissue specificity of Anisakis and two of its sibling species, A. simplex sensu stricto (s.s.) and Anisakis pegreffii, that are common in marine fish in Japanese waters. We orally challenged rainbow trout (Oncorhynchus mykiss (Walbaum)), and olive flounder (Paralichthys olivaceus (Temminck and Schlegel)) with L3 larvae of these two sibling species and monitored infection for 5weeks. In rainbow trout, A. simplex s.s., but not A. pegreffii larvae, migrated into the body muscle. A small number of freely moving A. pegreffii larvae were recovered within the body cavity. In olive flounder, A. simplex s.s. larvae were found in both the body cavity and body muscle. A. pegreffii larvae were found only in the body cavity and primarily encapsulated in lumps. Our results indicate that there are differences in the sites of infection and host specificity between the two sibling species of A. simplex s.l.

Direct competitive enzyme-linked immunosorbent assay (ELISA) for rapid screening of anisakid larvae in seafood

BACKGROUND

Anisakid larvae are one of the most important pathogenic parasites in marine products; however, simple and rapid analytical techniques for them are still very limited. In this research, based on specific rabbit polyclonal antibodies which were raised against crude extracts of Anisakis larvae, purified by protein A affinity chromatography and labeled with horseradish peroxidase, a direct competitive enzyme-linked immunosorbent assay (ELISA) was developed and validated for detection of anisakid larvae in seafood.

RESULTS

The established method exhibited a broad selectivity to Anisakis larvae and Pseudoterranova larvae, and the lowest detection limit to them was estimated to be about 5 parasites kg(-1) in food matrix. Using Pseudopleuronectes yokohamae, Scomberomorus niphonius and Ommastrephes bartrami as samples and within spiking concentrations from 20 to 100 larvae kg(-1), the determination recovery for Anisakis larvae and Pseudoterranova larvae ranged from 77.8% to 107.0%, with relative standard deviations all less than 20%.

CONCLUSION

The results allowed us to suggest the established direct competitive ELISA as an effective analytical tool for fast screening of anisakid larvae in sea foods.

[Larvae of Anisakidae nematodes and Trypanorhyncha cestodes of public health importance in Aluterus monoceros (Linnaeus, 1758) in Rio de Janeiro State, Brazil]

One hundred specimens of unicorn leatherjacket, Aluterus monoceros purchased from markets of municipalities of Niterói and Rio de Janeiro from May to August 2006. The fishes were measured, necropsied, fileted and analysed their organs. Sixteen fishes were parasitized by nematode Anisakidae: Anisakis spp. and Contracaecum sp. with respectively, 1 and 16% of prevalence, 2 and 3.31 of mean intensity, and 0.02 and 0.53 of mean abundance. Two larvae of Anisakis sp. were found in mesentery of one fish and Contracaecum sp. was found in liver and mesentery with 1 to 9 specimens of range of infection. Fifty-one fishes were parasitized on the liver and mesentery by metacestodes of Trypanorhyncha. The collected species were Floriceps saccatus and Callitetrarhynchus speciosus with respectively, 45 and 6% of prevalence, 3.17 and 2.83 of mean intensity, and 1.43 and 0.06 of mean abundance, the range of infection by F. saccatus was 1 to 20 and by C. speciosus was 1 to 5. Anisakis sp. and these two species of Trypanothyncha were reported in A. monoceros for the first time.

Multiple acute parasitization by Anisakis simplex

Hypersensitivity to Anisakis is an increasingly prominent medical problem throughout the world, due to a better understanding of diseases induced by parasites and to modern culinary habits of eating raw or undercooked fish. We describe the case of a patient who presented epigastric pain, wheals, erythema, and pruritus 3 hours after the ingestion of fish. More than 200 larvae were obtained by endoscopy. However, the patient only developed an immune response with specific immunoglobulin E and eosinophilia peaking at day 18 and decreasing during the 17-month follow-up. Only eosinophilia reached normal limits.

[On the infecstation of musculature in the Pacific salmons from Okhotsk Sea at early sea stage of their life]

Data on the infection of the musculature of juvenile salmons Oncorhynchus gorbuscha (Walbaum, 1792) and O. keta (Walbaum, 1792) with the nematode Anisakis sp. l. and cestode Diphyllobothriidae gen. sp. l. in Okhotsk Sea and adjacent Pacific waters are given. Probable regions where the infestation of juvenile salmons may take place are established. Interspecific differences in the levels of infestation, as well as differences in the invasion of fishes during their migration to ocean are revealed.

Pathological and ultrastructural studies on anisakis simplex rudolphi-1809 infecting Carangoides bajad with special reference to intestinal maturation in puppies

Thirty five (70%) of 51 Carangoides bajad were naturally infected with Anisakis simplex during the period from September 2007 to January 2008. The fish were collected from eastern south coast of the Red Sea at Hurgada. The morphological and ultrastructures of Anisakis larvae and adults, and the induced lesions in the fish (intermediate host), five puppies (final host) were orally given infected fish. The body of the larvae is gradually tapering towards the anterior part. It is covered by striated ornamentation longitudinally and horizontally, except the anterior region which is smooth. The morphological and ultrastrutural examinations of the anterior body end of larvae showed a prominent boring tooth, 3 pairs of lips inconspicuous and an excretory ventral pore between the rudimentary subventral lips. The anal end showed a distinct mucron and a slit-shaped anus. The pathological studies revealed encapsulated larvae with concentrical fibrous connective tissue infiltrated, with macrophages and lymphocytes on the surface of liver, spleen and peritoneum of the infected fish. The macrophages aggregated together to form the denser part of the capsule, and invaded the adjacent parenchymal tissue. The hepatocytes, under the affected capsule were necrotic and invaded by melanomacrophages.

Anisakis simplex: from obscure infectious worm to inducer of immune hypersensitivity

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.

Molecular detection of sibling species in anisakid nematodes

The number of sibling species of anisakid nematodes detected over the last two decades has been increased, fuelled by the use of genetic/molecular methodologies. In the present review, we summarize the biological species discovered within most of the nominal species belonging to the genera Anisakis, Contracaecum and Pseudoterranova by the use of allozyme (20-24 loci studied) and recently confirmed by us using mitochondrial cox-2 gene sequence analysis (mtDNA cox-2). Ecological evidence relating to the distributional range of the genetically detected sibling species and their host preferences, which represent data sets that can be utilized for species delimitation and definition, are summarized.

Immune reactions and allergy in experimental anisakiasis

The third-stage larvae (L3) of the parasitic nematode, Anisakis simplex, have been implicated in the induction of hyperimmune allergic reactions in orally infected humans. In this work, we have conducted a review of an investigation into immune reactions occurring in animals experimentally infected with A. simplex L3. The patterns of serum antibody productions in the experimental animals against excretory-secretory products (ESP) of A. simplex L3 contributed to our current knowledge regarding specific humoral immune reactions in humans. In our review, we were able to determine that L3 infection of experimental animals may constitute a good model system for further exploration of immune mechanisms and allergy in anisakiasis of humans.

Anisakis simplex: CO2-fixing enzymes and development throughout the in vitro cultivation from third larval stage to adult

We studied the effect of CO(2) on the in vitro cultivation of Anisakis simplex, an aquatic parasitic nematode of cetaceans (final hosts) and fish, squid, crustaceans and other invertebrates (intermediate/paratenic hosts), and, occasionally, of man (accidental host). The results showed that a high pCO(2), at a suitable temperature, is vital for the optimum development of these nematodes, at least from the third larval stage (L3) to adult. After 30 days cultivation in air, molting to L4 (fourth larval stage) was reduced to 1/3, while survival was about 1/3 of that when cultivated in air + 5% CO(2). The activity of the CO(2)-fixing enzymes, PEPCK and PEPC, was also studied. Throughout the development of the worms studied, PEPCK activity was much higher than that of PEPC (e.g., 305 vs. 6.8 nmol/min.mg protein, respectively, in L3 collected from the host fish). The activity of these enzymes in the worms cultivated in air + 5% CO(2) was highest during M3, and was also generally higher than that of those cultivated in air only, especially during molting from L3 to L4 (e.g., in recently molted L4, PEPCK activity was 3.7 times greater than that of PEPC 2.9 times greater than when cultivated in air).

Parasites as biological tags in population studies of demersal and pelagic fish species

Among the different techniques applied in a holistic approach for fish stock identification, the use of parasites as "biological tags" is becoming increasingly important. In this presentation, our recent studies on the use of some parasite species, identified by genetic markers, and the parasite/fauna composition, in stock identification of demersal (Merluccius merluccius), small pelagic (Trachurus trachurus), and large pelagic fish species (Xiphias gladius) are reviewed. Different species of Anisakis and Hysterothylacium were genetically identified by the application of genetic (allozyme) markers. Statistically significant differences in the spatial distribution of distinct species of Anisakis were found in the fish considered. As to the species of Hysterothylacium genetically detected, different relative proportions were detected in several Mediterranean and Atlantic samples of swordfish (X. gladius). This study demonstrates the potential value of these anisakid nematodes, at both larval and adult stages, as "biological tags" for these fish species in European waters.

Scanning electron microscopy of Anisakis larvae following different treatments

Ingestion of fish parasitized with Anisakis larvae can produce infestation and/or allergy in consumers. Technological and food processing treatments have been applied to parasitized fish in order to kill the larvae and avoid the infestation; however, their influence on allergenicity has not been studied. Four lots of hake (Merluccius merluccius) steaks artificially parasitized with Anisakis larvae were subjected to two storage chilling (5 degrees C +/- 1 degrees C) and freezing (-20 degrees C +/- 1 degrees C) treatments and two food processing treatments of heat (final temperature 86.3 degrees C) and microwave (final temperature 66.9 degrees C) and studied by scanning electron microscopy, environmental scanning electron microscopy (ESEM) (acid [pH = 2] and water preparations), and emission of fluorescence. Anisakis larvae were resistant to acid conditions, remaining alive after treatment. Larvae in the heat- and microwave-treated lots presented coagulated and disrupted zones in the cuticle with release of fluids. The cylindrical shape changed to a dehydrated appearance mainly observed by ESEM. Fluorescence was only noticeable in the frozen larvae. Larvae without apparent changes, together with dehydrated ones, were observed by ESEM in the frozen lot; nevertheless, no disruptions in the cuticle were perceptible. Further studies are needed in order to elucidate if the changes observed in the cuticle reduce the resistance of the parasites to the action of gastric enzymes in the gastrointestinal tract and to determine the release of allergens to the flesh by the live larvae during chilled storage of the fish.

New locality records for third-stage larvae of Anisakis simplex (sensu lato) (Nematoda: Ascaridoidea) in euphausiids Euphausia pacifica and Thysanoessa raschii from Prince William Sound, Alaska

Five euphausiid species (n=41,037) were collected in October 1997 from Prince William Sound, Alaska, and examined for parasites. New locality records are claimed for third-stage larvae (L3) of whaleworm Anisakis simplex (sensu lato) in two (0.019%) of 10,437 Thysanoessa raschii, and in one (0.013%) of 7,443 Euphausia pacifica. The L3 were about 19.5, 21.3 and 30.5 mm long. L3 were absent from 8,026 T. inermis, 10,302 T. longipes and 4,829 T. spinifera collected at the same time, and from 6,648 euphausiids representing the five species collected in July 1998. No individual harboured more than one parasite-a whaleworm L3, the ellobiopsid Thalassomyces fagei, a trypanorhynchid (tetrarhynchid) cestode (probably Nybelinia sp.), or a possible rhizocephalan. Controversy regarding the number of moults that occur in the egg of marine ascaridoids is discussed briefly.

[Anisakidae larvae (Nematoda: Ascaridoidea) parasites of the bluewing searobin Prionotus punctatus (Bloch, 1793) (Osteichthyes: Triglidae) from the coastal zone of the State of Rio de Janeiro, Brazil]

Eighty specimens of Prionotus punctatus (Bloch, 1793) from Angra dos Reis, coastal zone of the State of Rio de Janeiro (23 degrees 01 'S, 44 degrees 19 'W), were necropsied to study their metazoan parasites. Three species of larval nematodes anisakids were found, Anisakis sp., Hysterothylacium sp. and Raphidascaris sp. from the liver and mesenteries. These nematodes are described and a revision of available literature concerning nematodes belonging to these genera was made.

Survival of Anisakis simplex in arrowtooth flounder (Atheresthes stomia) during frozen storage

Survival of naturally occurring larvae of Anisakis simplex in fresh arrowtooth flounder (Atheresthes stomia) was determined after storage for specified periods at four freezing temperatures. All larvae were killed by 96, 60, 12, and 9 h at temperatures of -15, -20, -30, and -40 degrees C, respectively. The average percentages of live larvae per fillet at the next shortest holding time were as follows: 72 h at -15 degrees C, 0 to 3%; 48 h at -20 degrees C, 11 to 30%; 9 h at -30 degrees C, 5%; and 6 h at -40 degrees C, 0 to 3%. Larval survival was directly related to fillet thickness or weight (P < or = 0.05). Larval death was directly correlated to freezing temperatures. Holding time necessary to kill larval nematodes decreased as storage temperature decreased.

A new procedure for marinating fresh anchovies and ensuring the rapid destruction of Anisakis larvae

The consumption of marinated anchovies is the main route of transmission of anisakiasis in Spain. Because this country is one of the world's major tourist destinations, this traditional food also poses a potential health risk to millions of foreign visitors. Anisakis larvae are not destroyed by the traditional marinating procedure, and alternative methods, such as long-term storage in brine, freezing, or hydrostatic pressure treatment, all present major difficulties. In this study, we used high food-grade acetic acid concentrations (10, 20, 30, and 40% [vol/vol] in line with the quantum satis rule) to destroy these larvae rapidly, and we report data on the survival of Anisakis larvae exposed directly to different marinades and when the larvae are placed under the fish musculature. The percentage of salt and acetic acid in the fish tissue water phase was also determined. A marinating procedure is proposed that ensures the rapid death of Anisakis through the use of strong acetic acid concentrations. Posttreatment washes with water reduce these to levels acceptable to consumers. The sensory characteristics of the product were shown to be satisfactory. The actual selection of an acetic acid concentration for marinating depends on costs and the processing time available. The physiological stress of the larvae exposed to the different marinades was determined by measuring the levels of their stress proteins. The latter are good indicators of injury and might reflect the infectivity of larvae. In addition, we also used a rat model to determine the infectivity of larvae considered microscopically dead.

CO(2)-fixing enzymes during moulting from third larval to fourth larval stage of Anisakis simplex and Hysterothylacium aduncum (Nematoda: Anisakidae)

The fixing of CO(2) is an important metabolic process for many organisms. In the anisakid nematodes, CO(2) has been shown to be necessary for their development, at least in vitro. The presence of CO(2) stimulates the moulting (M3) of the larvae from the third (L3) to the fourth (L4) stage and prolongs the survival, at least, in vitro. We determined the activity of CO(2)-fixing enzymes, common to many organisms, in two anisakids: Anisakis simplex, a parasite of cetaceans, and Hysterothylacium aduncum, a parasite of fish. Although no activity was detected for pyruvate carboxylase or carboxylating-malic enzyme, we detected phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (PEPC) activity. In A. simplex, PEPCK was clearly higher than that of PEPC throughout the moulting process studied. In H. aduncum, although the activity of both enzymes was of similar magnitude, they showed different behaviour; PEPCK activity decreased after the moulting to L4, PEPC activity increased so that the ratio PEPCK/PEPC activity decreased from 1.90 before moulting to 0.59 after.

[Survival of the third stage larvae of anisakis simplex in various conditions and experimental infection in rats]

OBJECTIVE To observe the characteristics of biology and pathogenicity of the third stage Anisakis simplex larvae (L3).

METHODS

The survival time of the L3 in various conditions was observed and the pathological change after experimental infection in rats was examined.

RESULTS

The results showed that the L3 frozen at -20 degrees C for 10 - 12 h can be killed. In the temperature range of 4 - 10 degrees C, the L3, can survive for over 8 months. The L3 was very active at 37 degrees C, and was killed at the high temperature over 40 degrees C in a very short time. The ingredients for sashimi cannot kill the L3. The experiment of rats infected by the L3 showed that about 15% -25% of the L3 penetrated into the gastrointestinal wall or migrated into the peritoneal cavity in 2 days. After 3d the L4 was not infectious, and died automatically in 7 - 10 days and could not develop into adults. The animals can be easily infected when the stomach was empty. The pathological study showed that the primary infection was a kind of reaction to foreign body, while that of the re - infection was allergic.

CONCLUSION

The L3 has a strong resistance to low temperature and to ingredients, it can be killed by freezing at -20 degrees C in 24 hours. The L3 can not mature in the body of terrestrial mammals but causes pathological change in the stomach and allergy.

Population structure of Anisakis simplex (Nematoda) in harbor porpoises Phocoena phocoena off Denmark

The population structure and habitat selection of Anisakis simplex in 35 harbor porpoises off Denmark are described. The nematodes were collected from the stomach and duodenal ampulla and were categorized as third-stage larvae, fourth-stage larvae, subadults, and adults. The porpoises harbored 8,043 specimens of A. simplex. The proportion of adults and subadults increased with infrapopulation size. The number of development stages across infrapopulations covaried significantly (Kendall's test of concordance). Concordance was higher in hosts with the highest intensities than in those with low and medium intensities. All stages occurred mainly in the forestomach, but this trend was stronger for the adults. Adult and subadult sex ratios did not depart significantly from 1:1. Our data suggested that recruitment and duration of each stage were the main factors accounting for infrapopulation structure. The preference of A. simplex for the forestomach conformed with previous studies, but the narrower distribution of adults relative to other stages might indicate a strategy to enhance mating opportunities. Information on sex ratios of A. simplex is scarce and contradictory. We suggest that the discrepancies might partly reflect differences in categorization criteria and statistical methods.

The life cycle of Anisakis simplex in the Norwegian Deep (northern North Sea)

Copepoda (Calanus finmarchicus n = 1,722, Paraeuchaeta norvegica n = 1,955), Hyperiidae (n = 3,019), Euphausiacea (Meganyctiphanes norvegica n = 4,780), and the fishes Maurolicus muelleri (n = 500) and Pollachius virens (n = 33) were collected in the Norwegian Deep (northern North Sea) during summer 2001 to examine the importance of pelagic invertebrates and vertebrates as hosts of Anisakis simplex and their roles in the transfer of this nematode to its final hosts (Cetaceans). Third stage larvae (L3) of A. simplex were found in P. norvegica, M. muelleri and P. virens. The prevalence of A. simplex in dissected P. norvegica was 0.26%, with an intensity of 1. Prevalences in M. muelleri and P. virens were 49.6% and 100.0%, with mean intensities of 1.1-2.6 (total fish length >or=6.0-7.2) and 193.6, respectively. All specimens of C. finmarchicus and M. norvegica examined were free of anisakid nematode species and no other parasites were detected. P. norvegica, which harboured the third stage larvae, is the obligatory first intermediate host of A. simplex in the investigated area. Though there was no apparent development of larvae in M. muelleri, this fish can be considered as the obligatory second intermediate host of A. simplex in the Norwegian Deep. However, it is unlikely that the larva from P. norvegica can be successfully transmitted into the cetacean or pinniped final hosts, where they reach the adult stage. An additional growth phase and a second intermediate host is the next phase in the life cycle. Larger predators such as P. virens serve as paratenic hosts, accumulating the already infective stage from M. muelleri. The oceanic life cycle of A. simplex in the Norwegian Deep is very different in terms of hosts and proposed life cycle patterns of A. simplex from other regions, involving only a few intermediate hosts. In contrast to earlier suggestions, euphausiids have no importance at all for the successful transmission of A. simplex in the Norwegian Deep. This demonstrates that this nematode is able to select definite host species depending on the locality, apparently having a very low level of host specificity. This could explain the wide range of different hosts that have been recorded for this species, and can be seen as the reason for the success of this parasite in reaching its marine mammal final hosts in an oceanic environment.

Growth, fecundity and sex ratio of adult whaleworm (Anisakis simplex; Nematoda, Ascaridoidea, Anisakidae) in three whale species from the North-East Atlantic

The growth rate, fecundity, and sex ratio of Anisakis simplex in minke whales (Balaenoptera acutorostrata), porpoises (Phocoena phocoena) and long-finned pilot whales (Globicephala melas) was studied on the basis of material from the North Atlantic. A total of 8,135 mature A. simplex were collected from 24 minke whales, 11 porpoises and eight pilot whales. For both males and females, the prevalence was 100% for all three host species, with a mean intensity of 1,727, 262 and 139, respectively. The mean body length of adult female A. simplex was 126 mm in minke whales, 71 mm in the porpoises and 73 mm in pilot whales; and for males the averages were, respectively, 106 mm, 57 mm and 68 mm. Eggs from the uteri of 32 females of length 87-176 mm collected in minke whale stomachs were counted in a Fuchs-Rosenthal chamber. Total egg production was measured in 14 females cultivated at sea. The female growth period was estimated to be 30-60 days, and apparently all eggs were shed during the last week of life. A female of size 150 mm produces approximately 1.5 million eggs. In the cultivation experiment, about 85% of the total egg production was shed during the first 3 days after spawning started.

High hydrostatic pressure treatment of finfish to inactivate Anisakis simplex

High hydrostatic pressure has been demonstrated to be a useful technique for treating food to reduce the number of pathogenic organisms and to extend shelf life. Most research in this area has focused on bacteria. However, a concern in the sashimi (raw fish) industry is that nematode worms such as Anisakis simplex occur naturally in cold-water marine fish. The objectives of this research were to perform a pilot study to determine the effect of high hydrostatic pressure on the viability of Anisakis simplex larvae, commonly found in king salmon and arrowtooth flounder, and to evaluate the effects of high hydrostatic pressure on the color and texture of the fish fillets. Pieces of fish (ca. 100 g per bag) containing 13 to 118 larvae were exposed to pressures of up to 80,000 lb/in2 (552 MPa) for up to 180 s. The times and pressures required to kill 100% of the larvae were as follows: 30 to 60 s at 60,000 lb/in2 (414 MPa), 90 to 180 s at 40,000 lb/in2 (276 MPa), and 180 s at 30,000 lb/in2 (207 MPa). For all salmon treatments that killed 100% of the larvae, a significant increase in the whiteness of the flesh was observed. Although high hydrostatic pressure was effective in killing A. simplex larvae in raw fish fillets, its significant effect on the color and overall appearance of the fillet may limit its application to the processing of fish for raw-fish markets.

A case of acute gastric anisakiasis provoking severe clinical problems by multiple infection

Acute gastric anisakiasis with multiple anisakid larvae infection is reported. A 68-year-old woman residing in Busan, Korea, had epigastric pain with severe vomiting about 5 hours after eating raw anchovies. Four nematode larvae penetrating the gastric mucosae in the great curvature of the middle body and fundus were found and removed during gastro-endoscopic examination. Another one thread-like moving larva was found in the great curvature of upper body on the following day. On the basis of their morphology, the worms were identified as the 3rd stage larvae of Anisakis simplex. This case is acute gastric anisakiasis provoking severe clinical problems by the multiple infection and the greatest number of anisakid larvae found in a patient in Korea.

[Gastrointestinal anisakiasis. Study of a series of 25 patients]

INTRODUCTION

Infection with the parasite Anisakis simplex is common in Japan and northern European countries. The number of reported cases in Spain has increased since the first description in 1991. The aim of the present study was to evaluate the incidence, clinical patterns, histopathological lesions, treatment, and outcome of Anisakis simplex infection in our environment.

MATERIAL AND METHOD

Cases of gastrointestinal anisakiasis diagnosed in our center from December 1999 to January 2002 were studied. Only patients with detection of the parasite in oral endoscopy or the surgical specimen and those with elevated levels of specific IgE to Anisakis simplex, a clinical picture compatible with anisakiasis, or a history of raw fish intake were included. Epidemiological, clinical and laboratory data, as well as diagnostic, histopathologic and therapeutic features, and outcome in these patients were recorded.

RESULTS

Twenty-five cases of gastrointestinal anisakiasis were diagnosed during the study period, representing an incidence of 3.87 cases per 100 000 inhabitants/year. All the patients had ingested raw anchovies. Two groups were observed. The first group was composed of 10 patients with a gastric form of the infection, in which the main symptom was epigastralgia (90%). Oral endoscopy was performed in all patients and the parasite was detected in five (50%). The second group was composed of 15 patients with intestinal involvement in which the main manifestations were symptoms mimicking appendicitis (80%). The most frequent finding of laparotomy and/or imaging tests (abdominal ultrasonography, intestinal transit, abdominal CAT) was terminal ileitis (80%). Seven patients underwent surgery: intestinal resection was performed in four with detection of Anisakis simplex in three. Eosinophilic infiltration was found in all surgical specimens. Treatment was symptomatic in most of the patients and outcome was favorable in all.

CONCLUSIONS

Infection with Anisakis simplex should be investigated in patients with abdominal pain after intake of raw fish, ileitis of unclear origin, or eosinophilic gastroenteritis.

Growth of whaleworm (Anisakis simplex, Nematodes, Ascaridoidea, Anisakidae) third-stage larvae in paratenic fish hosts

The growth of Anisakis simplex L3 larvae in the three paratenic hosts saithe ( Pollachius virens), cod (Gadus morhua) and redfish (Sebastes marinus) was studied based on material collected off the island of Vega on the west coast of Norway over a period of 1 year. In all three fish species, a positive correlation between the length of larvae and the age of the fish was shown. The number of large larvae, here defined as L3>28 mm, increases with increasing age of the host. These findings clearly indicate an accumulation of large L3 larvae and larval growth in the fish host. The larvae were additionally grouped according to the tissue--muscle, liver or other viscera--they were located in. When the average lengths of the three groups of larvae were compared, the gadoids saithe and cod had somewhat higher values for L3 larvae found in the liver. Redfish, on the other hand, which store fat to a relatively higher degree in the viscera, had the highest average length of larvae in this tissue. The lowest average values in all three species were found in the musculature. These trends suggest that the growth of A. simplex L3 larvae is positively correlated with the fat content of the tissue in which it is encapsulated. Of the three host species included in this study, saithe seemed to be the best suited for A. simplex L3, as the growth rate and average length of the parasite was greatest in this species. The growth and average length of L3 was least pronounced in redfish while cod held an intermediate position.

Anisakis y anisakiosis

The nematode Anisakis simplex (AS) is a world wide distributed parasite that infects consumers of raw or undercoocked parasitized fish. The clinical manifestation of Anisakiosis depend on the site in the digestive tract in which larva lodges. The symptoms develops as a result of the inflammation when the larvae penetrates the gastric mucous. Most of asymptomatic subjects show high levels of specific IgE to AS. Diagnosis of AS allergy is not simple, due to cross-reactivity with other allergens. In childhood is more difficult to make a right diagnosis than in adult population. Most of positive prick test to AS correspond to children with positive prick tests to other allergens. Cross-reactivity between this parasite and other parasites with a higher prevalence in childhood, is the cause of a false diagnosis. The secretor-excretory antigen shows a better specificity, recognizing the true parasitized patients. This antigen could be used as indicator of parasitization. To follow prevention rules AS, avoid consumption of raw fish unless frozen for 48 hours or ingestion of fresh fish always cooked for more than 20 minutes at least at 60 C.

Human anisakiasis: Diversity in antibody response profiles to the changing antigens in larval excretions/secretions

Anisakiasis is an infectious parasitic disease contracted by eating third stage larvae of Anisakis simplex (L3) carried by marine fishes. Human anisakiasis was researched for specific IgG with L3 excretory secretory products (ESP). L3ESP were prepared by daily harvesting of culture supernatant from day 2 to day 5, using two kinds culture media of RPMI-1640 and phosphate buffered saline (PBS). When the sera from persons diagnosed with anisakiasis by means of endoscopy were analyzed using indirect ELISA and Western blot, the sera was classified into four groups depending on specific antigen recognition patterns. In addition, the presence of a new antigen for L3, located at less than 13 kDa (AgLT13) was demonstrated in L3ESP with a modified Western blot condition. The production of AgLT13 was mainly found in L3ESP harvested both on day 2 and day 3, and that in PBS was predominant over that in RPMI-1640. Among those sera, the high reactive sera to L3ESP-day two prepared with phosphate buffer in indirect ELISA recognized AgLT13, and 33% of the low reactive sera did so. These results indicate that the binding pattern of human L3 specific antibody is diverse depending on L3ESP preparations and that AgLT13 demonstrated with a Western blot condition is a specific antigen for L3.

The nematode Anisakis simplex in American shad (Alosa sapidissima) in two Oregon rivers

This paper represents the first report of the nematode Anisakis simplex in the American shad (Alosa sapidissima) in its introduced range in the American Pacific Northwest. All the adult shad sampled from spawning populations in the Willamette (n = 9) and Umpqua (n = 12) rivers were infected with A. simplex with intensities ranging from 6 to 89 worms per fish. This preliminary investigation contrasts sharply with previous studies in the native range of American shad and confirms that this fish may be an important intermediate host for A. simplex in the Pacific Northwest. It is suggested that this new parasite-host relationship has led to an ecological expansion into rivers and Anisakis may present an emerging health risk for wildlife and some human consumers.

[Allergy to Anisakis simplex]

Anisakis simplex is a nematode which infects marine fish. It requires marine mammals for its development. The larvae are found in fishes, crustaceans and cephalopods which are intermediate hosts. The parasite can be ingested by man -mainly with raw fishes- and induces an infestation called anisakiasis or anisakidosis with digestive tract symptoms. Since 1990, we have known that the parasite can also induce allergic symptoms such urticaria.

Effects of ivermectin and albendazole against Anisakis simplex in vitro and in guinea pigs

The activity of ivermectin and albendazole against larval Anisakis simplex was tested in vitro and in experimentally infected guinea pigs. Before drug exposure the medium for half of the larvae was adjusted to pH 2.0 with 1 N HCl, whereas the other half was held at pH 7.0. To these solutions, ivermectin was added to full concentrations of 1, 2, 5, 10, 50, 100, or 200 microg/ml, and for albendazole, 300, 400, and 500 microg/ml. Animals from group I were given 0.1 ml of 1% (3.3 mg/kg) ivermectin, whereas guinea pigs from group II were each given 5-7 mg (16.6-23.3 mg/kg) of albendazole orally. The efficacy of both drugs against L, A. simplex was high in vitro and in vivo against the larvae in different organs of guinea pigs.

Anisakis simplex larva killed by high-hydrostatic-pressure processing

Anisakis simplex is a common nematode parasite present in many marine fish, including finfish and squid. It can pose a public health problem if it is not destroyed during food processing. Anisakis larvae were isolated from fish tissue, and their survival of high-pressure treatments in distilled water and physiological isotonic solution was assayed. Treatment at a pressure of 200 MPa for 10 min at a temperature between 0 and 15 degrees C kills all Anisakis larvae, with a lack of motility being used as an indicator of larval death. Lower pressures can be successfully employed down to 140 MPa, but with lower pressures, the treatment time must be increased by up to I h to kill all larvae. Meanwhile, most larvae treated for >10 min at pressures of >120 MPa were dead, with the autofluorescence method being used to determine death. Cycles of compression and decompression increase the destruction of larvae compared with a single pressure treatment for a similar treatment time. Our results indicate that high-pressure treatment is an alternative nonthermal method for killing this nematode. The possible mechanism of death and damage by pressure is discussed, and uses for this treatment in food processing are suggested.

In vitro cultivation of anisakis simplex: pepsin increases survival and moulting from fourth larval to adult stage

This paper describes the in vitro cultivation of the 3rd-larval stage (L3) of Anisakis simplex to adulthood in a much simpler and easier to prepare medium than those described to date. The adult males obtained are between 3.8 and 6.5 cm long and the females between 4.5 and 8.0 cm. Some individually cultivated females laid eggs which had an average size of 44.4 x 50.5 microm. The culture conditions were as follows: medium RPMI-1640 supplemented with 20% heat-inactivated fetal bovine serum and 1% commercial pepsin, at pH 4.0 and a temperature of 37 degrees C, and in air atmosphere with 5% CO2. The pepsin was found to be the key to the success of the culture. The average survival of the worms in the culture increased from 50 to 88 days, due to the fact that the survival of the adults practically doubled (increasing by 1.9 times). Furthermore, the number of worms that completed the 4th moulting (M4) increased by 4.2 times, from 22.9 to 95.6%. This culture medium may facilitate, due to its simplicity, the study of anisakids, or at least of A. simplex, constituting another step towards achieving a complete in vitro life-cycle for these parasites.

Element concentration variability in the whaleworm Anisakis simplex s.l

Concentrations of the elements C, N, Fe, Na, K, Ca and Mg were analysed by chromatography and atomic absorption spectrometry in the whaleworm Anisakis simplex sensu lato. Nearly all mean inorganic element concentrations measured were higher in adult worms than in larval forms. Similarly, adults contained significantly higher nitrogen (i.e. lower C/N ratio values) than either eggs or larvae. Evidence for the significance of the parasitic life cycle stage and the systematic position of their hosts on the element concentration variability is discussed.

Fitness of the marine parasitic nematode Anisakis simplex s. str. in temperate waters of the NE Atlantic

In temperate waters of the NE Atlantic, third-stage larvae of Anisakis simplex sensu stricto collected from 3 paratenic host species were identified by restriction fragment length polymorphisms. The condition of wild larval infrapopulations was assessed by examining morphometric and growth characteristics. The differentiation patterns and the excretory/secretory products of larvae grown in vitro were also examined. An extensive morphometric, growth and differentiation variability was found between parasite larvae collected from different paratenic host sources. Nematode infrapopulation larvae from the squid comprise those smaller individuals with the lowest values of survival rates and moult success. It may be then concluded that the fitness of A. simplex s. str. larvae is not the best possible in the squid, which impaired the competitiveness of the parasite and its chances of developing into an adult. This suggests that the microenvironments impaired by the paratenic host may provide larval infrapopulations with unique ecological factors probably influencing its recruitment to the final host populations.

Anisakis infestation in marine fish and cephalopods from Galician waters: an updated perspective

A total of 2,673 fresh specimens of cephalopod and fish representing 35 species were obtained from commercial local fisheries in Galician waters (NW Spain). They were examined for anisakid nematodes by digestion of the muscle and elution of the viscera and whole body cavity. All larval nematodes recovered were identified by light microscopy and multilocus electrophoresis as belonging to the species Anisakis simplex sensu stricto and A. pegreffii. Encysted larvae mostly occurred in the viscera but were also found in the flesh of squid and fish. Demographic values for larval nematodes are discussed in relation to host preferences and the ecological niche of both anisakid species at the sampling area. Primary recommendations are also expressed concerning the effects of current fishing and aquaculture practices on the Anisakis problem.

[Anisakiasis: a borderline disorder]

Anisakis simplex is a nematode which can parasitize many different kinds of fish or cephalopods (codfish, salmon, tuna, mackerel, hake, etc). Anisakis simplex can cause different diseases in humans. The human being acquires the larvae by eating raw or undercooked seafood. Acute anisakiasis is probably caused by an inflammatory and/or allergic response in the digestive tract mucosa with abdominal pain. It can also induce IgE-mediated reactions with several clinical manifestations ranging from urticaria/angioedema to anaphylaxis. Chronic anisakiasis results from abscesses or eosinophilic granulomas caused by parasite invasion. This later form can mimic appendicitis, duodenal ulcer, inflammatory bowel diseases and intestinal obstruction. An early gastroduodenoscopy can confirm the diagnosis and prevent the complications. Serodiagnosis of anisakiasis is difficult since many Anisakis antigens show cross-reativity complications. In fact many people have high IgE titles in the absence of obvious allergic reactions to seafoods. As preventive measures heating for 10 min over 65 degrees C or freezing (minus 20 degrees for 24 h) destroys the infectivity of the larval stage but not always prevent allergic reactions.