Search Results (20)

In the last 25 years, nematode parasites of the genus Anisakis have attracted international attention from various socio-economic sectors, with serious concern about the impact of these parasites on seafood quality and safety, and public health (related to both zoonoses and allergy). A knowledge-based understanding of the population structure of Anisakis spp. is useful to provide valuable data about the infection dynamics, host specificity and its ability to adapt to local environments and to climate change by adapting to the food-web structure. This study first aimed to investigate the taxonomic biodiversity of Anisakis spp. collected from commercial fish and cetacean species from the most significant Northeast Atlantic fishing grounds and evaluate the ecological connections of A. simplex and A. pegreffii (L3 and adults) in cetaceans and fish from NW Spain, through the analysis of their genetic diversity and population structure. A total of 1399 Anisakis spp. L3 larvae from six fish species and 475 adults from six cetacean species were identified using the ITS rDNA region as a molecular marker. Molecular identification allowed for the first detection of A. berlandi in European waters parasitizing the long-finned pilot whales Globicephala melas and the first report of A. nascettii and A. zhiphidarum infecting the striped dolphin Stenella coeruleoalba, as well as the identification of A. simplex, A. pegreffii and the hybrid genotype between both species. The analysis of the mitochondrial cytochrome oxidase 2 gene of A. simplex and A. pegreffii, the most prevalent species in FAO area 27, revealed panmictic populations for both species with high haplotype diversity. The predatory–prey relationship involving two major fish species (European hake and blue whiting) and the common dolphin appears to provide an important mechanism for maintaining genetic diversity and structure in major Anisakis species in the NE Atlantic. Full article

This study employs molecular detection techniques, including conventional PCR and Sanger sequencing, to investigate the prevalence, species composition and public health implications of Anisakid nematodes in blue whiting (Micromesistius poutassou) caught off the Portuguese coast. With Portugal’s high fish consumption rates and increasing preference for raw or undercooked seafood, the risk of parasitic infections, particularly anisakidosis, is rising. Fifty blue whiting fish were examined, showing a 100% infection rate with Anisakid larvae. Molecular analysis identified 68.1% of the larvae as Anisakis simplex, 18.1% as Anisakis pegreffii, and 13.8% as Hysterothylacium aduncum, marking the first report of H. aduncum in blue whiting in Portugal. Phylogenetic analysis based on the internal transcribed spacer (ITS) 1, 5.8S ribosomal RNA and ITS-2 confirmed the species classification. Notably, 42.9% of the fish were infected with multiple Anisakid species, increasing the risk of allergenic sensitization. Statistical analysis showed no significant correlation between fish width and parasitic load, and a weak negative correlation was found between fish length and parasitic load. The study contributes to food safety by integrating molecular tools that enable rapid and accurate species identification, offering new insights into the detection of biological contaminants in seafood. These findings are significant considering the rising trend in raw seafood consumption, underscoring the urgent need for enhanced detection strategies and broader parasite monitoring programs to mitigate public health risks. The high prevalence of parasitized fish highlights the necessity for the implementation of safe cooking practices to reduce the risk of anisakidosis. Further research into the allergenic potential of Hysterothylacium spp. and the ecological factors influencing this nematode distribution is recommended. Full article

The longjaw tapertail anchovy Coilia nasus, which migrates from ocean to freshwater for spawning in spring, is an important anadromous fish with ecological and cultural significance. To determine parasite infection in anadromous C. nasus, a total of 103 fish from the Yangtze River were collected and examined in 2021 and 2022. The overall infection prevalence of nematodes in C. nasus was 100%, with a mean intensity of 13.81 ± 16.45. The mean intensity of nematode infections in 2022 was significantly higher than that observed in 2021 across all sampling sites (p < 0.05). Nematodes were widely detected in the mesentery, pyloric cecum, stomach, and liver, among which the mesentery accounted for the highest proportion, reaching up to 53.52%. A total of eight ascaridoid nematodes belonging to the family Anisakidae and Raphidascarididae were identified by using morphological characters and molecular biological techniques, including two species of Anisakis, five species of Hysterothylacium, and one species of Raphidascaris. A. pegreffii was found as the predominant species, accounting for 48.65% of all identified parasitic nematodes in liver, while Raphidascaris sp. was the most common nematode in the mesentery, pyloric cecum, and stomach, reaching up to 39.81%, 36.21%, and 74.36%, respectively. The present study systematically investigated the parasitic status and community structure of the nematode in C. nasus during its migration in the Yangtze River. This research provides a foundation for studying the impact of nematode parasitism on the reproductive migration and population recruitment of C. nasus, and offers valuable insights for biomarker screening and nematode identification in C. nasus. Full article

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. Full article

Nematodes of the genus Anisakis (Rhabditida, Anisakidae) are zoonotic fish-borne parasites and cause anisakiasis, a disease with mild to severe acute or chronic gastrointestinal and allergic symptoms and signs. Anisakiasis can potentially lead to misdiagnosis or delay in diagnosis, and it has been suggested as a risk factor for gastrointestinal tumors. Here, we describe a case report of a 25-year-old woman who presented with gastrointestinal (abdominal pain, nausea, diarrhea) and allergic (diffuse skin rash) symptoms and reported ingestion of raw fish contaminated by worms. Gastro and colon endoscopy allowed the visualization and removal of nematodes and collection of bioptic tissue from ulcers and polyps. The removed nematodes were molecularly identified as Anisakis pegreffii. The patient was treated with chlorphenamine maleate, betamethasone, omeprazole, paracetamol, albendazole. We conclude that an upper endoscopy matched with a colonoscopy and molecular characterization of the pathogen yields the most reliable diagnosis and treatment for human anisakiasis, enabling the complete removal of the larvae and preventing chronic inflammation and damage. Full article

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. Full article

The European hake, one of the most commercially valuable species in ICES fishing areas, is considered an important neglected source of zoonotic risk by nematode parasites belonging to the genus Anisakis. Merluccius merluccius is, by far, the most important host of Anisakis spp. at the European fishing grounds, in terms of demographic infection values, and carries the highest parasite burden. These high parasite population densities within an individual fish host offer a chance to explore new sources of variations for the genetic structure of Anisakis spp. populations. A total of 873 Anisakis spp. third-stage larvae, originally sampled from viscera and muscular sections of hake collected at ten fishing grounds, were primarily identified using ITS rDNA region as molecular marker. After that, we used mtDNA cox2 gene to reveal the high haplotype diversity and the lack of genetic structure for A. simplex. Dominant haplotypes were shared among the different fishing areas and fish sections analyzed. Results indicate a clear connection of A. simplex from European hake along the Northern North Sea to the Portuguese coast, constituting a single genetic population but revealing a certain level of genetic sub-structuring on the Northwest coast of Scotland. This study also provides useful information to advance the understanding of parasite speciation to different fish host tissues or microenvironments. Full article

Spotted flounder (Citharus linguatula L.) caught in the Gulf of Cadiz (area FAO 27 ICES IXa) were examined for Anisakis larvae and to assess the possible risk of anisakiasis in humans through consumption of this fish. Larvae of the genera Anisakis and Hysterothylacium were identified in the analysis of 128 purchased fish specimens. All Anisakis larvae corresponded to type I. Molecular analysis showed the presence of A. pegreffii, A. simplex s.s., and recombinant genotype between the two. The prevalence of Anisakis was 9.4% with a mean intensity of 1.42, while for Hysterothylacium the values were 12.5% and 1.06. The length and weight of the fish, but not Fulton’s condition factor, varied significantly between infected and uninfected fish. The prevalence of Anisakis increased with fish length, with no fish parasitized with Anisakis measuring less than 15.5 cm (2–2.5 years old), which is probably related to the reported dietary change of these fish at around 2 years of age. Fish not parasitized with any of these nematodes showed positive allometric growth, while those parasitized only with Anisakis showed negative allometric growth. When comparing both groups including only fish ≥ 15.5 cm (the smallest size of Anisakis-infected fish), the difference is shown to be statistically significant (p = 0.01), suggesting that Anisakis infection of spotted flounder negatively affects fish growth even when parasite intensity is low, which may have important economic repercussions. Finally, the low prevalence and, above all, intensity of Anisakis in these fish, as well as the habit of consuming this fish fried in oil in our geographical area, means that the risk of acquiring anisakiasis through consumption of this fish is low. Full article

The study aimed to perform the molecular identification of Anisakis larvae in commercial fish from the coast of the Canary Islands and to provide data on their infection level for the host and the species of this nematode parasite that we could find in several species of commercial interest in the Canary Archipelago. Fish specimens (n = 172) from the Canary coasts were examined for parasites. In total, 495 larvae were identified; PCR was carried out for the entire ITS rDNA and cox2 mtDNA region, obtaining sixteen sequences for the entire ITS rDNA region and fifteen for the cox2 mtDNA, this being the first contribution of nucleotide sequences of Anisakis species of fish caught from the Canary Islands. An overall prevalence of 25% was obtained in the fish analyzed, and five species of Anisakis were identified, these being Anisakis simplex (s.s.), Anisakis pegreffii, Anisakis physeteris, Anisakis nascettii and Anisakis typica and the hybrid Anisakis simplex x Anisakis pegreffii. The results obtained in this study have relevance for public health, since the pathology will depend on the species of Anisakis, so it is important to know the health status of fish in the waters of the Canary Islands to assure a safer consumption and take adequate measures, in addition to the provision of epidemiological data. Full article

Parasitic nematodes of the genus Anisakis are among the most important biological hazards associated with seafood. A survey of Anisakis spp. in European hake (Merluccius merluccius) was undertaken as this species is a staple of the Portuguese diet. Moreover, a literature review of cases of anisakiosis reported from Portugal, a country with one of the highest levels of fish consumption in the world, was also carried out. Seventy-five European hake caught in the Atlantic Ocean off the northern coast of Portugal were analyzed to determine the infection levels and site distribution of Anisakis spp. Isolated nematode larvae were identified to species level by molecular analysis. Two sets of samples were collected. Firstly, a total of 46 Anisakis spp. L₃ larvae were collected with a prevalence of 76.7% (95% CI 61.5–91.8%) and intensity (mean ± SD, range) of 2.0 ± 1.2 (1–5). Most larvae were found on the liver (45.7%) and on the gonads (32.6%), but none in the muscle. The molecular analysis showed the presence of both A. simplex s.s. (70%) and A. pegreffii (30%). For the second sample, analyzed using the UV-Press method, a total of 473 Anisakis spp. were found, with a prevalence of 95.6% (95% CI 89.5–100.0%), intensity (mean ± SD, range) of 11.3 ± 9.7 (1–41), density of 0.05 ± 0.04 (0–0.16) worms/muscle weight in g, and density of 0.54 ± 0.50 (0–2.53) worms/viscera weight in g. Surprisingly, only three very recent cases of human anisakiosis in Portugal have been reported in the literature. Data from this study contribute towards an updating of the existing epidemiological picture in an area characterized by very high seafood consumption and changing eating habits. Full article

The aim of the present study was to describe gastric granuloma caused by Anisakis pegreffii in Sphyraena viridensis caught in the central Mediterranean Sea. Sixty-eight S. viridensis specimens were collected from different fish markets on the east coast of Sicily. Coelomic organs were observed both macroscopically and with the aid of stereomicroscope. Parasite specimens and lesioned tissues were collected for identification, histological and molecular analyses. Twelve specimens (p = 17.6%) were positive for the presence of nematode larvae, morphologically identified as larvae of Anisakis sp., with values of mean abundance and mean intensity of 0.9 and 4.8, respectively. One large female specimen showed massive parasite infection associated with nodular lesions of the gastric wall. By histology, several nematode larvae encysted through the gastric wall were found. The parasite bodies were surrounded by a granulomatous reaction made up of macrophages, epithelioid cells, some lymphocytes and an external connective sheet. Molecular analysis of 18S rRNA and cox2 genes from Anisakis sp. collected larvae, identified them as A. pegreffii. The lesions here described, though macroscopically superimposable on human eosinophilic granuloma, microscopically showed significant differences in the inflammatory cells involved and in the type of immune reaction. Full article

The sibling species Anisakis simplex (s.s.) and Anisakis pegreffii are parasites of marine mammals and fish worldwide and the main causative agents of human anisakiasis. In sympatric areas, a hybrid genotype between the two species has been identified, mainly in third-stage larvae, but rarely in fourth-stage and adult forms. The aim of this study was to confirm the presence of hybrid genotypes in larvae parasitizing fish caught in sympatric and allopatric Spanish marine waters, the North-East Atlantic and West Mediterranean, respectively, and to study possible differences in the growth behaviour between genotypes. Of the 254 molecularly analysed larvae, 18 were identified as hybrids by PCR-RFLP analysis of the rDNA ITS region, 11 of which were subsequently confirmed by EF1 α-1 nDNA gene sequencing. These results therefore indicate an overestimation of hybrid genotypes when identification is based only on the ITS region. We also report the detection of a hybrid specimen in a host from the West Mediterranean, considered an allopatric zone. Additionally, fourth-stage larvae with a hybrid genotype were obtained in vitro for the first time, and no differences were observed in their growth behaviour compared to larvae with A. simplex (s.s.) and A. pegreffii genotypes. Full article

Anisakis simplex (s.l.) is a complex of three sibling (biological) species of parasitic nematodes of marine mammals, including A. berlandi, A. pegreffii and A. simplex (s.s.). It is characterized by a complex life cycle in which humans can become accidental hosts by consuming dishes made of raw or undercooked fish containing L3 larvae, which in many regions of the world is related to the national or regional culinary tradition. This has spurred scientific efforts to develop new methods for treating the disease, called anisakiasis, and to neutralize invasive L3. Thiabendazole (TBZ) is a wide-spectrum anthelminthic with a higher efficacy than albendazole, a drug whose long-term use induces resistance in many parasitic species. Cytochromes P450 participate in TBZ metabolism, and the expression of their genes is controlled by nuclear hormone receptors (NHR). This study aimed to examine the effects of TBZ on the above-described pathway in invasive larvae of A. simplex (s.l.). The efficacy of TBZ against A. simplex (s.l.) larvae was observed for the first time. Larvae were cultured in vitro for 72 h in a medium containing TBZ at five concentrations from 0.5 to 1.5 mM. However, the survival curves did not significantly differ from each other. This means that all of the concentrations of TBZ had a similar effect on the A. simplex (s.l.) L3 larvae during in vitro culture. Nevertheless, TBZ modified the expression of nhr-48, cyp13a3 and cyp1a1 genes in the L3 of A. simplex (s.l.). Full article

The study aims to perform, for the first time, the molecular identification of anisakid larvae in commercial fish from the Southeastern Pacific Ocean off the Peru coast, and to provide data on their infection level by fishing ground, fish host, and site of infection. Fish specimens (N = 348) from the northern and the central coast of Peru were examined for parasites. The fish fillets were examined by the UV-press method. Anisakis spp. larvae (N = 305) were identified by mtDNA cox2 sequences analysis and by the ARMS-PCR of the locus nas10 nDNA. Two hundred and eighty-eight Anisakis Type I larvae corresponded to Anisakis pegreffii, whereas 17 Anisakis Type II larvae clustered in a phylogenetic lineage distinct from Anisakis physeteris deposited in GenBank, and corresponding to a phylogenetic lineage indicated as Anisakis sp. 2, previously detected in fish from both Pacific and Atlantic waters. Anisakis pegreffii was found to infect both the flesh and viscera, while Anisakis sp. 2 occurred only in the viscera. The average parasitic burden with A. pegreffii in the examined fish species from the two fishing grounds was significantly higher than that observed with Anisakis sp. 2. The results obtained contribute to improve the knowledge on the distribution and occurrence of Anisakis species in Southeastern Pacific waters and their implications in seafood safety for the local human populations. Full article

Sardina pilchardus and Engraulis encrasicolus are considered the principal target species for commercial fishing in Europe and are widely consumed as semipreserved products. Although they are considered shelf-stable products, if treatment is not correctly applied, their consumption may represent a public health risk in regard to anisakiasis and allergic reactions. Little is known about the prevalence of Anisakis spp. in ripened products. This study aimed to evaluate the presence of Anisakis spp. larvae in deboned, in-oil anchovy and sardine fillets marketed in the EU to assess the influence of processing techniques on the prevalence of larvae. Ninety semipreserved anchovy and sardine products deriving from the Mediterranean Sea or Atlantic Ocean were collected from different EU retailers and examined using chloropeptic digestion to evaluate the presence of larvae and identify them. Thirty nonviable Anisakid larvae—A. pegreffii (30%) and A. simplex (70%)—were found. The frequency of larvae was higher in anchovies (28.8%). The low frequency of parasites found proved that processing technologies can influence the presence of larvae in final products, but it is important that visual inspection is performed only by trained people. The sources of raw materials should be considered in the production flow chart. Full article