Anisakid Nematodes Research Articles

Genetic analyses of Anisakis pegreffii (Nematoda: Anisakidae) from the East Asian finless porpoise Neophocaena asiaeorientalis sunameri (Cetacea: Phocoenidae) in Korean waters

The East Asian finless porpoise, Neophocaena asiaeorientalis sunameri, is an endangered species that inhabits the coastal marine environments of East Asia. In the present study, we investigated the overall infection status of anisakid nematodes in East Asian finless porpoises from three sea sectors off the Korean Peninsula. The genetic diversity and population genetic structure of the identified nematode species were evaluated. The prevalence of all stages of anisakid nematodes collected from the stomach was 57.55% (61 among the 106 porpoises examined), and 16 of the hosts were found to have adult worms. The mean number of infected adults was 211 (± 419.54, 5–1455 per host). Only one species of anisakids, Anisakis pegreffii, was identified from randomly selected worms by molecular approaches. Analysis of the mitochondrial (mt) cox2 partial gene in 50 newly generated sequences of A. pegreffii revealed 24 haplotypes, including 14 new haplotypes. We observed below-average levels of nucleotide diversity and haplotype diversity compared to other seas around the world. The mtDNA cox2 haplotypes of the species in the three Korean sea areas showed no genetic structure, suggesting well-connected gene flow within these areas. This study represents the first record of a definitive host of A. pegreffii in Korean waters, providing important information regarding anisakids genetic diversity in the cetacean species inhabiting limited regions.

Anisakid nematode larvae in freshwater fishes in the St. Lawrence River (Québec, Canada)

Anisakid nematodes were observed in freshwater and anadromous fishes in the St. Lawrence River, Québec, Canada. Fish were caught at different locations across a 250 km gradient in the St. Lawrence ecosystem covering freshwater and estuarine habitats. Depending on the sampling sites, nematode prevalence ranged from 30% to 58% for sauger (Sander canadensis) and was 43% for Atlantic tomcod (Microgadus tomcod). For walleye (Sander vitreus), parasites were found only in a fluvial Lake (Lake Saint-Pierre) of the St. Lawrence River, with a prevalence of 23%. In all sampling sites, mean abundance of nematodes in the flesh was higher in sauger than in walleye. Presence of nematodes was significantly correlated with fish total length for walleye, sauger and Atlantic tomcod. Sealworm, Phocanema decipiens s.s., and whaleworm, Anisakis simplex s.s., were found and identified by molecular analysis in sauger and walleye in a fluvial lake (Lake Saint-Pierre), the fluvial estuary and the upper estuary of the St. Lawrence River, while Atlantic tomcod were found infected in a freshwater river tributary (Sainte-Anne River) during spawning.This is the first record of Ph. decipiens s.s. in a non-anadromous freshwater fish. The presence of sealworm and whaleworm in walleye and sauger is attributed to their forays into the brackish waters of the fluvial estuary and suggest large scale migrations between the brackish and the fresh waters of the St. Lawrence River.

Use of stable isotope ratio analysis to investigate the biology and clinical significance of seal parasites.

Stranded seals are often infected with a broad range of parasites, although whether they are the cause of significant morbidity or an incidental finding is usually unclear. In this study we used stable isotope ratio analysis, a method frequently used to investigate food webs, to explore the extent to which common seal parasites feed directly on host tissue and fluids or absorb host-derived metabolites, which in turn may give an indication of their potential impact on the host's health. The trophic discrimination factor Δ15N for the nasal mite, Halarachne halichoeri, was mostly positive, ranging between −0.015 and 3.2‰ (n = 6), while for the Acanthocephalan worm, Corynosoma strumosum and the anisakid nematode, Pseudoterranova decipiens, Δ15N ranged between −4.2 and −2.0‰ (n = 7), and between −6.7 and −0.8‰ (n = 5) respectively. In the case of the lungworm, Otostrongylus circumlitus, Δ15N measured between −5.6 and 0‰ for worms collected in the stomach (n = 5), between −1.1 and 0.2‰ for worms collected from the heart (n = 3), between −0.7 and 1.9‰ for worms situated in the lungs (n = 4). Based on Δ15N, parasites could be clearly divided into those that were on a higher trophic level than their host suggesting a predator–prey-like relationship, and those that were not. It is hypothesized that Δ15N may be indicative of the clinical significance of parasite–host associations.

Identifikasi Anisakis sp. pada Cumi-cumi (Loligo spp.) di Pasar Wuring dan TPI Kota Maumere

Maumere City is one of the largest squid producers in NTT with a total production and catch of 143,958 tons. Squid has various health benefits, but squid is also susceptible to parasitic infections such as Anisakis sp.. Anisakis sp. is an anisakid nematode that can cause anisakiasis, which is zoonotic and dangerous to humans. This study aims to determine the type and calculate the prevalence of Anisakis sp. on squid (Loligo spp.) traded at Pasar Wuring and TPI Maumere City. The collection used the sampling quota method with a total sample of 100 squids divided into 5o samples at Wuring Market and 50 samples at TPI Maumere City. The sample was then necropsy to look for the presence of Anisakis sp. on internal organs of the body. The parasite was found collected in a Petri dish containing NaCl, then fixed with 70% alcohol, stained with Semichon’s acetocarmine, then dehydrated and stratified with 70% alcohol, 85% 95%. Next, identify it under a microscope. The results showed that the type of parasite that infects squid is Anisakis sp. type I, characterized by clear boring teeth, ventriculus, and mucron. The prevalence of Anisakis sp. in squid is 11% which belongs to the category of frequent predilection organs on the muscular wall of the anterior mantle, liver, and muscular wall of the caudal coat.

Anisakid parasite diversity in a pygmy sperm whale, Kogia breviceps (Cetacea: Kogiidae) stranded at the edge of its distribution range in the Northeast Atlantic Ocean.

Anisakid nematodes are a globally distributed group of marine mammal parasites. Kogiid whales, including the pygmy sperm whale Kogia breviceps, host an assemblage of specific anisakid species. Currently, three species are known to be specific to kogiid hosts, i.e., Skrjabinisakis paggiae, S. brevispiculata, and the less studied Pseudoterranova ceticola. The aim of this study was to investigate the species diversity of anisakid nematodes sampled from a pygmy sperm whale stranded in 2013 at the edge of its distribution range in the Northeast Atlantic, specifically in the North of Scotland. Nematodes were assigned to genus level based on morphology and identified by sequence analysis of the mtDNA cox2 gene and the rDNA ITS region. The present finding represents the first observation of syntopic occurrence of adult stages of S. brevispiculata, S. paggiae, and P. ceticola in a pygmy sperm whale in the Northeast Atlantic, and represent the northernmost record of these species in this area. Skrjabinisakis brevispiculata was the most abundant species, accounting for 55% of the identified nematodes, predominantly in the adult stage. Anisakis simplex (s.s.) was also abundant, with most specimens in the preadult stage, followed by S. paggiae and P. ceticola. The pygmy sperm whale is rarely documented in Scottish waters, and its occurrence in the area could suggest expansion of its geographic range. The presence of S. brevispiculata, S. paggiae, and P. ceticola in this whale species in this region may indicate a shift in the whole host community involved in the life cycle of these parasites in northern waters. However, it is also plausible that these parasites were acquired while the whale was feeding in more southern regions, before migrating northbound.

Multidisciplinary approach to the diagnosis of Contracaecum magnipapillatum infections in Australian black noddies, Anous minutus (Charadriiformes: Laridae)

We provide the incidental necropsy findings associated with anisakid nematode infections of black noddy terns, Anous minutus Boie, 1844 (Charadriiformes: Laridae), from offshore islands in the southern Great Barrier Reef, Queensland, Australia. Specimens collected from the proventriculi were identified morphologically as Contracaecum magnipapillatum Chapin, 1925 (Rhabditida: Anisakidae), using light and scanning electron microscopy (SEM). The entire nuclear ribosomal DNA internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) was amplified by polymerase chain reaction (PCR) and sequenced to provide reference sequences for morphologically well-identified voucher specimens. Interestingly, after an alignment with closely related taxa using BLAST, sequences of the ITS1 and ITS2 were 100% identical to the sequences assigned to Contracaecum septentrionale Kreis, 1955, from a razorbill, Alca torda Linnaeus, 1758 (Charadriiformes: Alcidae), from Spain. These results either raise questions about the ITS as a genetic marker for some members of Contracaecum, or the identity of the specimens assigned to C. septentrionale, given that no supporting morphological data was associated with them. We highlight the need for a combined morphological and molecular approach to parasite diagnostics and the use of multiple genetic loci to resolve the molecular taxonomy of cryptic species. Morphological identifications should be taxonomically robust, transparent and precede the deposition of molecular barcodes in public repositories. The gross and histopathological findings of our investigation concur with previous reports of widespread Contracaecum infections in black noddies and support the contention that Contracaecum spp. are an unlikely primary cause of mortality.

An Epidemiological Update on Anisakis Nematode Larvae in Red Mullet (Mullus barbatus) from the Ligurian Sea.

Red mullet (Mullus barbatus) is a commercially relevant fish species, yet epidemiological data on anisakid nematode infestation in M. barbatus are scarce. To fill this gap, we report the occurrence of Anisakis larvae in red mullet in the Ligurian Sea (western Mediterranean). This survey was performed between 2018 and 2020 on fresh specimens of M. barbatus (n = 838) from two commercial fishing areas (Imperia, n = 190; Savona, n = 648) in the Ligurian Sea. Larvae morphologically identified as Anisakis spp. (n = 544) were characterized using PCR-RFLP as Anisakis pegreffii. The overall prevalence of A. pegreffii was 24.46%; the prevalence at each sampling site was 6.32% for Imperia and 29.78% for Savona. Furthermore, 3300 larvae of Hysterothylacium spp. were detected in the visceral organs of fish coinfected with A. pegreffii, showing that coinfection with two parasitic species is not rare. This study provides a timely update on the prevalence of ascaridoid nematodes in red mullet of the Ligurian Sea, an important commercial fishing area in the Mediterranean.

Oral intake of a widely available gastrointestinal OTC medicine ‘Seirogan’ is effective for gastric anisakiasis (Anisakis food poisoning)

Gastric food poisoning due to anisakid nematodes (gastric anisakiasis) is characterized by severe stomach pain caused by the consumption of raw fish that harbors anisakid nematodes. The only effective treatment that is currently available is the endoscopic removal of nematodes penetrating the stomach wall. An in vitro study showed that the widely available over-the-counter (OTC) gastrointestinal medicine 'Seirogan' containing wood creosote kills Anisakis larvae. In addition, two cases in which the oral intake of Seirogan alleviated gastric anisakiasis symptoms have been reported. Herein, we analyzed 56 statements regarding Seirogan's efficacy against gastric anisakiasis posted on social networking sites (SNSs) in Japan. There were 33 statements (59%) that Seirogan was effective in significantly alleviating or eliminating symptoms of gastric anisakiasis, 13 comments (23%) stating that it had a slight effect, and 10 comments (18%) stating that there was no effect. These results indicate that in many cases, an oral intake of Seirogan is effective as first aid to remove or alleviate severe stomach pain due to gastric anisakiasis.

Infection levels of Gnathostomatidae (Nematoda) larvae in commercial fishes in north-eastern Australian waters and related food safety concerns

The majority of research on the safety of marine edible fish has primarily focused on anisakid nematodes, neglecting the potential risks posed by other parasites, including those belonging to the family Gnathostomatidae. In Australia, there have been few reported cases of human infections with gnathostomatid parasites since 2011. However, due to the absence of a standardized diagnostic test in the country, it is believed that the actual number of infections is higher than reported. This study aimed to assess the occurrence and prevalence of infectious gnathostomatid parasites in selected commercial fish species in Australia. A total of 1947 marine fish from northern Australia, representing 9 families, 16 genera, and 30 species, were examined for gnathostomatid nematode infections. Overall, 12.3 % of the fish were found to be infected with at least one gnathostomatid larva. Among the species examined, the yellow-dabbled flounder (Branchypleura novaezeelandiae) exhibited the highest prevalence (83.3 %; n = 6) and the largest number of gnathostomatid larvae. The identification of the gnathostomatid larvae was confirmed as belonging to the genus Echinocephalus based on both morphological characteristics and sequence data. No significant correlation was observed between the prevalence, mean abundance, and mean intensity of infection with the length or weight of the examined fish species. Notably, several of the infected fish species are considered popular choices in the Australian market. Hence, it is imperative to raise awareness among relevant food safety authorities regarding the occurrence of these parasites. The findings from this study should be taken into consideration for the revision of current seafood safety protocols in the country.

Morphological and Molecular Characterization of Anisakid Nematode Larvae (Nematoda: Anisakidae) in the Black Cusk eel Genypterus maculatus from the Southeastern Pacific Ocean off Peru

The back cusk eel, Genypterus maculatus (Tschudi, 1846), (Ophiidiformes: Ophiididae) is one of the benthic-demersal fish usually consumed in northern Peru. Here, we identified the third stage (L3) Anisakidae sampled from 29 specimens of G. maculatus captured off the south American Pacific coast, Lambayeque Region, Peru. A total of 20 anisakid nematode larvae were collected on the visceral surface and divided morphologically into three types (Type I–III). These larvae were identified by mtDNA Cox2 sequences analysis, which indicated that corresponded to Anisakis pegreffii Campana-Rouget and Biocca, 1955, Skrjabinisakis physeteris (Baylis, 1923) and S. brevispiculata (Dollfus, 1966) Safonova, Voronova, and Vainutis, 2021, respectively. This is the first record of S. brevispiculata in Peru. The results obtained in this study provide knowledge on the diversity and distribution of Anisakis Dujardin, 1845 and Skrjabinisakis Mozgovoi, 1951, species in the south American Pacific waters and their relevance for public health. In addition, we suggest that combined use of molecular and morphological approaches is needed to characterize L3 anisakid larvae.

Seals, fish, humans and parasites in the Baltic: ecology, evolution and history.

Evolutionary and ecological processes affecting the interactions between hosts and parasites in the aquatic environment are at display in the Baltic Sea, a young and ecologically unstable marine ecosystem, where fluctuating abiotic and biotic factors affect the parasitofauna in fish. The dynamic infections of Baltic cod, a subpopulation of the Atlantic cod (Gadus morhua Linnaeus), with third stage anisakid nematode larvae of Pseudoterranova decipiens (Krabbe, 1878) and Contracaecum osculatum (Rudolphi, 1802) have increased following a significant increase of the Baltic grey seal Halichoerus grypus (Fabricius) population in the region. Cod serves as a paratenic host and marine mammals, pinnipeds, are definitive hosts releasing parasite eggs, with faeces, to the marine environment, where embryonation and hatching of the third stage larva take place. The parasite has no obligate intermediate hosts, but various invertebrates, smaller fish and cod act as paratenic hosts transmitting the infection to the seal. Contracaecum osculatum has an impact on the physiological performance of the cod, which optimises transmission of the larva from fish to seal. Thus, a muscle mass decrease of nearly 50% may result from heavy C. osculatum infections, probably amplified by a restricted food availability. The muscle atrophy is likely to reduce the escape reactions of the fish when meeting a foraging seal. In certain regions, where fish and seals are restricted in their migration patterns, such as the semi-enclosed Baltic Sea, the predation may contribute to a severe cod stock depletion. The parasites are zoonotic and represent a human health risk, when consumers ingest insufficiently heat- or freeze-treated infected products. Marked infections of the cod were previously reported during periods with elevated seal populations (late 19th and middle 20th century) and various scenarios for management of risk factors are evaluated in an evolutionary context.

Anisakid nematodes from the largehead hairtail fish (Trichiurus lepturus) from the northern coast of Java, Indonesia

Abstract. Setyobudi E, Murwantoko, Utami AMR, Syarifah RF. 2023. Anisakid nematodes from the largehead hairtail fish (Trichiurus lepturus) from the northern coast of Java, Indonesia. Biodiversitas 24: 1560-1568. Hairtail fish has been frequently reported to be infected by anisakid nematodes. This study aims to determine the presence of anisakid nematodes on the large-head hairtail fish (Trichiurus lepturus) from the northern coast of the Java Sea, Indonesia. In total, 306 hairtail fish were collected from the northern coast of Java. Each fish sample was measured its length and weighed, then dissected to examine the presence of anisakid nematode. The anisakid larva examination was conducted in the body cavity, internal organs, digestive tract, and muscles. The anisakid nematodes found were then separated and grouped based on morphological appearance, namely body color and size. Selected samples from each anisakid group and sampling location were extracted and identified molecularly by the direct sequencing method. The findings showed that the larvae of anisakid nematodes infect the T. lepturus with different prevalence and average intensity at each location (P: 38.0-100%, MI: 3.33-42.88 larvae/ind.). Mostly anisakid larvae were found in the body cavity and were not found in the muscle. Most of the T. lepturus from the northern coasts of Cirebon and Pati were infected with anisakid at low intensity (?5 larvae/individual). The high intensity of anisakid larval infection was shown by the hairtail originating from Rembang and Tuban (>20 larvae/ind.). Molecular identification showed that three anisakids were isolated from hairtails from the northern coast of Java, namely Anisakis typica, Hysterothylacium amoyense, and Raphidascaris lophii. Information on anisakid species and their distribution is important as a reference for fish handling and processing, the assessment of the human health risk, and the development of these nematodes as biological tags.

Complete Mitochondrial Genome of Contracaecum sp. (Nematoda: Ascarididae) from night herons in China

Contracaecum species are zooparasitic anisakid nematodes and occur in gastrointestinal tracts of vertebrate/invertebrate animals, including humans, causing gastrointestinal pain, diarrhea, and increasingly severe vomiting. Although the complete mitochondrial (mt) genome (mitogenome) of Contracaecum sp. isolated from night herons in Beijing has been reported, the detailed information about this mt sequence is still puzzling. In the present study, we described the detailed characteristics across the complete mt DNA of Contracaecum sp., which includes 36 genes consisting of 12 protein genes, 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and 2 noncoding regions (NCRs), and all genes have the same orientation of transcription. The AT content in the complete mitogenome of Contracaecum sp. was 72.2%, and it was the least value (66.7%) in the cox1 gene but was the highest rate (84.1%) in NCRs. The highest nucleotide diversity (Pi) among the genus Contracaecum was nad4 (0.190) and the least was cox1 (0.125), which indicates that nad4 might have the potential ability as useful markers to detect cryptic species in the genus Contracaecum or subspecies. Based on the maximum likelihood (ML) and Bayesian inference (BI) computational algorithms within subfamilies Ascaridoidea and Heterakoidea, the results supported that Contracaecum sp. was a new species and the family Ascaridiidae was paraphyletic. The complete mitogenome sequence of Contracaecum sp. supported a clear recognition of Contracaecum species and provided the potential existence of cryptic species in the genus Contracaecum. Our findings would better contribute to the surveillance, molecular epidemiology, and control of Contracaecum.

Anisakid nematodes in Trichiurus lepturus and Saurida undosquamis (Teleostea) from the South-West Indian Ocean: Genetic evidence for the existence of sister species within Anisakis typica (s.l.), and food-safety considerations

Nematode parasites of the genus Anisakis (Nematoda, Anisakidae) are considered among the most important biological hazards in seafood products worldwide. In temperate and tropical waters, the most common species appears to be Anisakis typica, generally found around the viscera and sporadically in the flesh of various fish host species. This study investigated the infection sites and genetic diversity of A. typica infecting commercial fishes from the South-West Indian Ocean. Largehead hairtail (N = 20) and brushtooth lizardfish (N = 72) fished off Tanzania were inspected for anisakid nematodes by UV-press. A subsample of 168 nematodes were identified by sequence analyses of the cox2 mtDNA gene and ITS region of rDNA. The species A. typica (s.l.) (N = 166), Pseudoterranova ceticola (N = 1) and Anisakis paggiae (N = 1) were molecularly identified. Phylogenetic analysis of A. typica (s.l.) sequences based on both genes, indicated the existence of two distinct phylogenetic lineages forming two well-supported clades. The first clade comprised 12 A. typica specimens including individuals from its type locality (central Atlantic Ocean). The second clade comprising 154 specimens, clustered with reference sequences retrieved from GenBank including one apparently undescribed taxon, i.e., Anisakis sp. 1, and A. typica var. indonesiensis. The two reciprocally monophyletic clades are closely related and correspond to two distinct sister species within A. typica (s.l.), presently indicated as A. typica sp. A and A. typica sp. B. Two and four fixed alternative nucleotide substitutions (SNPs), i.e., diagnostic positions, between the two taxa, respectively, were found at the mtDNA cox2 and the ITS region of rDNA. The genetic data, as well as their occurrence in sympatry, strengthens the hypothesis that the actual specimens represent two distinct gene pools. The occurrence of both A. typica sp. A and A. typica sp. B in the musculature of freshly examined T. lepturus and S. undosquamis, suggests that both species can migrate intra-vitam into the flesh. Although the zoonotic potential of A. typica s.l. is still unclear, the presence of these parasites in the musculature, edible part of the fish, raises health concerns for consumers.

Distribution and genetic diversity of Anisakis spp. in cetaceans from the Northeast Atlantic Ocean and the Mediterranean Sea

Parasite biodiversity in cetaceans represents a neglected component of the marine ecosystem. This study aimed to investigate the distribution and genetic diversity of anisakid nematodes of the genus Anisakis sampled in cetaceans from the Northeast Atlantic Ocean and the Mediterranean Sea. A total of 478 adults and pre-adults of Anisakis spp. was identified by a multilocus genetic approach (mtDNA cox2, EF1 α − 1 nDNA and nas 10 nDNA gene loci) from 11 cetacean species. A clear pattern of host preference was observed for Anisakis spp. at cetacean family level: A. simplex (s.s.) and A. pegreffii infected mainly delphinids; A. physeteris and A. brevispiculata were present only in physeterids, and A. ziphidarum occurred in ziphiids. The role of cetacean host populations from different waters in shaping the population genetic structure of A. simplex (s.s.), A. pegreffii and A. physeteris was investigated for the first time. Significant genetic sub-structuring was found in A. simplex (s.s.) populations of the Norwegian Sea and the North Sea compared to those of the Iberian Atlantic, as well as in A. pegreffii populations of the Adriatic and the Tyrrhenian Seas compared to those of the Iberian Atlantic waters. Substantial genetic homogeneity was detected in the Mediterranean Sea population of A. physeteris. This study highlights a strong preference by some Anisakis spp. for certain cetacean species or families. Information about anisakid biodiversity in their cetacean definitive hosts, which are apex predators of marine ecosystems, acquires particular importance for conservation measures in the context of global climate change phenomena.

Anisakis typica (DIESING, 1860), DOMINANT ANISAKID NEMATODE PRESENT IN SHORTFIN SCAD, Decapterus macrosoma (BLEEKER, 1851) FROM TERENGGANU WATERS, MALAYSIA

Anisakid (Anisakis spp.) nematode is a fish-borne parasite that can cause zoonotic disease, Anisakiasis and IgE hypersensitivity in humans. Thus, the ecology and epidemiology of Anisakis nematode are important to control this zoonotic infection. Although Anisakis larvae have been reported in Malaysia, it has not been studied through morphological characteristics and molecular analyses. The objective of this study was to identify the Anisakis species and its infection status in Decapterus macrosoma from Terengganu waters, Malaysia. All Anisakis larvae found were morphologically similar to each other and identified as Anisakis typica. High infection level (P = 100%, M.I. = 23.31±17.26) of A. typica was found in D. macrosoma. There was a bioaccumulation of A. typica in D. macrosoma, showing significant correlation of body weight (p = 0.05) and total body length (p = 0.02) with the amount of A. typica present in D. macrosoma. Interestingly, the gonad was the specific site of infection of A. typica in D. macrosoma, where the intensity of A. typica was significantly (p < 0.003) higher than other visceral organs. Therefore, the migration of A. typica depended on the fatty tissue of the organ.

Anisakis spp, DNA detection in paraffin-embedded tissue biopsies recovered from patients with gastritis using real-time PCR in Bushehr, Persian Gulf, Iran

Anisakiasis is a zoonotic fish-born parasitic disease caused by anisakid nematodes. Paraffin-embedded blocks containing biopsy samples taken from patients suffering gastritis with unknown causes were investigated by real-time PCR, in the Bushehr region, Iran; where human anisakiasis has not been reported, so far. A total of 50 paraffin-embedded blocks were randomly selected from 250 archived blocks of the patients with gastritis. A SYBER green-based real-time PCR targeting the ITS1 region was developed for the identification of Anisakis genus. An 86 bp partial fragment of the Anisakis spp. ITS1 gene was amplified successfully. A total of 3 out of 50 samples (6 %) had positive amplification in the samples and their pathology reports showed a significant finding of moderate chronic gastritis with or without ulcers. In conclusion, the developed qPCR could be used for detecting Anisakis spp. larval DNA in human biopsy blocks. This study showed the hidden human cases of anisakiasis in the Bushehr for the first time.

Anisakid Nematodes and Potential Risk of Human Anisakiasis through the Consumption of Hake, Merluccius spp., Sold Fresh in Spanish Supermarkets

Nematode parasite species belonging to the Anisakis simplex complex are the most important cause of human anisakiasis through the consumption of (mainly) undercooked, previously not frozen, or conveniently treated fish. In Spain, the consumption of hake has been recognized as an important source of this parasitosis. With the aim of shedding light on the risk factors that can influence the potential risk of human anisakiasis in Spain through the consumption of fresh hake sold by nationwide supermarket chains, a total of 536 small hake specimens belonging to the species Merluccius bilinearis caught off the Northeast American coasts and Merluccius merluccius caught in the Northeast Atlantic and Mediterranean waters was analysed. Anisakids morphologically identified as Anisakis type I were found as the most prevalent and the most abundant species and were considered the main potential cause of human anisakiasis. Intrinsic and extrinsic factors concerning the hake, such as its origin and season of capture, its size, as well as the days passed between its capture and consumption, should be taken into account to avoid this human parasitosis. It is essential that consumers have access to fish label information which should include, as regulated by the European Commission, traceability data.

Gene expression and allergenic potential of Pseudoterranova bulbosa L3 from different infection sites in North Atlantic cod (Gadus morhua)

The recent advances in molecular methods and data processing have facilitated research on anisakid nematodes. While most research efforts were made regarding the genus Anisakis, since this genus is held responsible for the majority of reported clinical signs, there is still a demand for data on the genus Pseudoterranova. Several case studies of severe invasive anisakidosis affecting various organs caused by species of the P. decipiens complex have been described. To better understand the way these parasites might infest their fish host, we examined whether parasite location within the fish host affects gene expression. A de novo assembly of the transcriptome of Pseudoterranova bulbosa, isolated from North Atlantic cod, was analysed for patterns of differential gene expression between samples taken from liver and viscera. We additionally searched for homologs to known nematode allergens, to give a first estimate of the potential allergenicity of P. bulbosa. There was a subtle difference in the gene expression of samples taken from liver and viscera. Seventy genes were differentially expressed, 32 genes were upregulated in parasites isolated from liver and 38 genes were upregulated in parasites from viscera. Homologs of five nematode allergens were identified among the genes expressed by P. bulbosa. Our transcriptome of P. bulbosa will be a valuable resource for further meta-analyses and resequencing projects.

Infections and molecular characterization of anisakid nematodes from two species of marine fish northwest Arabian gulf

The present study provides new insight into valuable information on the diverse structure of the anisakid population, discusses the limited species richness, and also discusses the relationship with other closely diversity-related taxa in NCBI databases in the Epinephelus diacanthus and Epinephelus coioides fish. The fishing area consists of various locations in the Arabian Gulf. A total of 69 E.coioides and E. diacanthus were examined, (n= 48) were infected. Larval stages (n=1,119). Isolated larvae were encysted within the mesenteries peritoneum and viscera of fish organs, with a prevalence of 81.25% of infection and 59.459 % in the E. diacanthus and E. coioides respectively. Molecular analysis was carried out on thirty individuals of nematode parasites who have examined the morphology and showed some appearance differences, by amplifying internal transcribed spacers ITS and ITS-1 of nuclear rDNA (rDNA) by PCR using the primer sets NC5/NC2 and SS1/NC13R of DNA products. Evolutionary analyses were conducted in MEGA X. based on the identity percentage in the GenBank database showed that they belong to anisakid nematodes, in particular, they belong to nine distinct taxa within the Hysterothylacium spp. The presence of the same species individuals in one host may be the cause of these genetic variations at the species level, and that's what the current study has recorded. It has been found that there is an overlap in the order of nitrogen bases between the same species, and this occurs through the fertilization process, while the rest is clean or have only a few parasites.