In order to know whether there is a risk of anisakiasis (or anisakidosis) by consumption of fish of the genus Mullus from the western Mediterranean Sea, which are appreciated for their quality, an epidemiological survey was carried out to evaluate the occurrence of zoonotic or potentially zoonotic nematodes in M. barbatus and M. surmuletus. Although the presence of the third larval stage (L3) of anisakids (Anisakis and Contracaecum) has been previously described in these fish, the results showed the absence of anisakids and the presence, never in muscle, of L3 and L4 of raphidascaridids of the genus Hysterothylacium, molecularly identified as H. fabri. Phylogenetic analysis groups them into the Mediterranean Sea clade, far from individuals isolated in the Pacific Ocean. Prevalence was slightly higher, but not significant, in M. barbatus versus M. surmuletus (72.3% vs 60.0%), but mean intensity (MI) and mean abundance (MA) parameters were approximately twice as high in M. barbatus as in M. surmuletus (MI 5.8 vs 2.8, p = .001; MA 4.2 vs 1.7, p < .001). The presence of the parasite seems to have different effects on these two sympatric species. In M. barbatus it seems to affect their growth, as it appreciably reduces the value of allometry coefficient in infected fish (2.78 vs. 2.18). On the other hand, in M. surmuletus the infection significantly (p < .04) affects the Fulton\'s condition factor, an indicator of the health status of the fish. It can be concluded that the ingestion of these fish by the people poses negligible risk of anisakiasis, but the consumer should continue to be urged to follow the rules of prevention against this illness.

The third-stage larvae (L3) of the Anisakidae family are parasitic nematodes with zoonotic impact and are frequently encountered in the organs and musculature of various fish intended for human consumption. Since Anisakis simplex (s.s.) and A. pegreffii are the major aetiological agents of human disease, this study aims to combine the morphological and molecular data on the recovered anisakid larvae to contribute to a simplified morphological distinction of those species and conducted a survey of anisakid larvae infection in horse mackerel (Trachurus trachurus). Here, 116 horse mackerel caught in Portuguese waters were analysed for the presence of L3 of anisakids, and 3148 larvae were collected, of which only 30% were retrieved during visual inspection. As such, visual inspection does not appear to be very effective in anisakid detection. A prevalence of 84.5% of infected fish was found, and the mean intensity and mean abundance were 32.1 and 27.1 parasites per fish, respectively. The morphological and molecular analyses of 196 L3 randomly chosen from the total sample of parasites demonstrated the presence of L3 of mostly Anisakis spp., with only one L3 of Hysterothylacium aduncum. Relative frequencies of 62.9% for A. pegreffii and 37.1% for A. simplex (s.s.) were obtained. The morphometry differences between these two sibling species were evaluated, and the results demonstrated significant differences between the length of the ventriculus and the length of the oesophagus. Precisely, A. simplex (s.s.) has a longer oesophagus and ventriculus than A. pegreffii. As such, these differences may be used to distinguish the two species through morphological analysis.

Despite increases in the annual consumption of seafood in Australia, studies on the occurrence and prevalence of zoonotic parasites in fish and the risk they may pose to human health are limited. The present study was aimed at determining the occurrence of zoonotic nematodes in commonly consumed fish in New South Wales, Australia\'s most populous state. Three species of fish, including the Australian pilchard, Australian anchovy, and eastern school whiting, were purchased from a fish market and examined for the presence of nematode parasites. All Australian pilchards examined in this study were infected (100%; n = 19), followed by the eastern school whiting (70%; n = 20) and Australian anchovy (56%; n = 70). Nematodes were in the larval stage and, therefore, classified by morphotype, followed by specific identification through sequencing of their internal transcribed spacer (ITS) regions. Seven different larval types with zoonotic potential, belonging to the families Anisakidae (Contracaecum type II and Terranova type II) and Raphidascarididae (Hysterothylacium types IV [genotypes A and B], VIII, XIV and a novel Hysterothylacium larval type, herein assigned as type XVIII), were found. The new larval type was identified as Hysterothylacium thalassini, based on ITS sequence data. The presence of the infective stage of a range of zoonotic parasites in fish commonly consumed in New South Wales is important, particularly as, in some dishes, these fish are used whole, raw or undercooked. This study provides the basis for future research on other aspects of these parasites, in regards to public health.

Raphidascaris (Sprentascaris) andersoni n. sp. (Nematoda: Raphidascarididae) collected in the intestine of the humphead cichlid Gymnogeophagus balzanii (Perugia) from the Pantanal wetlands, State of Mato Grosso do Sul (Brazil) is described and genetically characterized. The new species differs from its congeners mainly by having a conspicuous papilla-like formation slightly anterior to the cloacal aperture. Furthermore, males of R. (S.) lanfrediae and R. (S.) mahnerti have caudal alae, and R. (S.) hypostomi and R. (S.) pimelodi lack lateral alae, whereas in the new species caudal alae are absent and lateral alae present. The remaining congeners, namely, R. (S.) marano and R. (S.) saltaensis differ from Raphidascaris (Sprentascaris) andersoni n. sp. mainly because males have three pairs of postcloacal papillae (vs five pairs). In the phylogenetic reconstructions, using three nuclear genetic markers (18S, ITS1-5.8S-ITS2 and 28S rDNA) and one mitochondrial (cox1 mtDNA), the new species was separated from other representatives of Raphidascarididae, and the absence of monophyly in Hysterothylacium and Raphidascaroides was confirmed. Moreover, the subgenera Sprentascaris and Ichthyascaris appeared to be monophyletic. Therefore, even though Raphidascaris (Raphidascaris) was apparently not monophyletic, the subgenera of Raphidascaris should be re-erected as valid genera. The updated diagnoses of Ichthyascaris, Raphidascaris and Sprentascaris are given. The present study represents the first parasitological survey in G. balzanii.

Zoonotic fish-borne nematodes are a significant and growing global health concern. However, in Australia their occurrence and geographical distribution are not well known. Moreton Bay in Queensland, Australia, is a popular tourist destination for domestic and international visitors where seafood is a popular food item. The aim of this study was to determine the occurrence of zoonotic nematodes within four commercially significant teleost fish species from Moreton Bay; Surf Bream, Sea Mullet, Yellow-Fin Tripod fish and Gold-Lined Sea Bream. Overall, 34.03% of fish examined (n = 144) were found to be a host to at least one parasitic nematode. The seasonal dynamics and prevalence of nematode infection was tested by statistical means. Results indicated a significant difference in seasonal infection for Surf Bream (p < 0.005) only. Several potentially zoonotic larval morphotypes were found, including Contracaecum types I and II, and Terranova type II (Family Anisakidae), and Hysterothylacium types VI and XIV and a new Hysterothylacium larval type herein assigned as type XVII (Family Raphidascarididae). ITS sequence data showed that some Contracaecum type II and Hysterothylacium types VI found in the present study are genetically distinct from those previously reported. The new genotypes were assigned to Contracaecum type II Genotype B and Hysterothylacium type VI, Genotypes B and C. This study provides essential information for future research on specific identification and differentiation of infective stages of zoonotic nematoda in edible fish.

Studies of nematofauna of teleost fish from the Brazilian coast are relatively scarce and limited to identification based on morphology. The objective of the present study was to determine the diversity and prevalence of nematode parasites in teleost fish from the southeast Atlantic coast of Rio de Janeiro, through morphological, molecular, and ecological approaches. Parasites were collected from sixty specimens each of Genypterus brasiliensis, Micropogonias furnieri, and Mullus argentinae obtained in winters and summers of 2012–2014. Morphological and genetic characterization was conducted using light microscopy and the molecular targets 18S rDNA, ITS1, and mtDNA cox2. Nematodes identified in M. furnieri were Cucculanus genypteri (n = 1575, P = 98.3%) and Hysterothylacium deardorffoverstreetorum (s.l.) (n = 2, P = 3.3%); in G. brasiliensis were Dichelyne (Cucullanellus) sciaenidicola (n = 99, P = 33.3%), Cucculanus pulcherrimus (n = 45, P = 18.3%), Hysterothylacium deardorffoverstreetorum (s.l.) (n = 3, P = 5%), and Anisakis typica (n = 1, P = 1.7%); and, in M. argentinae, were H. deardorffoverstreetorum (s.l.) (n = 146, P = 48.3%), and Procamallanus (Spirocamallanus) halitrophus (n = 4, P = 6.7%). DNA sequence data of C. genypteri, C. pulcherrimus, D. (C.) sciaenidicola, and P. (S.) halitrophus were reported for the first time. New host records are M. argentinae for P. (S.) halitrophus, M. furnieri for A. typica, while H. deardorffoverstreetorum (s.l.) was found in all three fish species. Intestine showed significantly higher intensity than other sites, and no significant seasonal variation in parasitological indices was observed. Hysterothylacium specimens (n = 6) were found in fish muscle, potentially a public health concern.

The cinnamon flounder Pseudorhombus cinnamoneus is a frequently consumed marine fish in China. However, the occurrence of ascaridoid larvae in P. cinnamoneus remains unclear. In the present study, a total of 85 P. cinnamoneus caught from the Yellow Sea (off Shidao, 36°52\'57″N, 122°26\'42″E) in 2011, which is located between mainland China and the Korean Peninsula, was investigated for ascaridoid larval infection. Four ascaridoid larval types, including Anisakis type I of Berland (1961), Hysterothylacium type of Smith (1983), Hysterothylacium type HL of Guo et al. (2014) and Raphidascaris type of Zhao et al. (2016), were detected in this important food fish. These larval types were identified as Anisakis pegreffii, Hysterothylacium aduncum, H. sinense and Raphidascaris lophii, respectively, using PCR-based restriction fragment length polymorphism (PCR-RFLP) analysis and sequencing of the ITS region of nuclear ribosomal DNA (rDNA). The third-stage larvae of H. sinense are reported from Chinese waters for the first time. The prevalence of H. sinense was 100% and represents the predominant species of the ascaridoid larvae found in P. cinnamoneus. The prevalences of A. pegreffii and H. aduncum were 44.7% and 81.2%, respectively. Phylogenetic analyses based on ITS sequences were performed to elucidate the genetic relationships of these ascaridoid nematodes. The present study increases the knowledge and distribution of ascaridoid larvae in this area of Yellow Sea. The high prevalence of ascaridoid larvae in P. cinnamoneus shows that an assessment needs to be undertaken to assess the risk these parasites may pose to public health.

Thirty-six Paralichthys patagonicus and 30 Xystreurys rasile were collected in the state of Rio de Janeiro, Brazil to investigate the presence of anisakid and raphidascaridid nematodes. Anisakis typica, Terranova sp., Contracaecum sp., Hysterothylacium deardorffoverstreetorum, and Raphidascaris sp. were identified using integrative taxonomy of morphological and genetic data. Morphological and morphometric analysis was conducted using bright field microscopy with scanning electron microscopy for topographic characterization of the cuticular surface. Phylogenetic analysis, using ITS and cox2 molecular targets, clearly demonstrated the species identification of A. typica and H. deardorffoverstreetorum and the high diversity of H. deardorffoverstreetorum. This is the first report of A. typica, H. deardorffoverstreetorum, and Raphidascaris sp. parasitizing P. patagonicus and X. rasile.

Here we report occurrence of six different morphotypes of ascaridoid type larvae from 28 species of fish collected from New Caledonian waters. The larvae were morphologically identified as Anisakis type I, Hysterothylacium type VI and new larval types XIII and XIV, Raphidascaris larval type and Terranova larval type II. Representatives of each morphotype were subjected to the amplification of the second internal transcribed spacers (ITS-2) of ribosomal DNA (rDNA) and those sequences were compared with ITS-2 sequences of other ascaridoid nematodes previously deposited in GenBank. ITS-2 sequences of Anisakis larval type I were identical to those of A. typica. ITS-2 sequences of Hysterothylacium larval type VI in the present study were identical to those previously found in Eastern Australian waters. No match was found for ITS-2 sequences of Hysterothylacium larval types XIII and XIV; therefore, the specific identities of these larval types remain unclear. ITS-2 sequences of Raphidascaris larval type were identical to those of R. trichiuri, which have previously been reported in Taiwanese waters. Terranova larval type II in the present study had identical ITS-2 sequences with Terranova larval types reported from Australian waters, however, the specific identity is unknown. This taxonomic work is essential if further research on these zoonotic parasites is to be effective. This includes investigations into such aspects as life cycle studies, impacts on human health and risk assessment for their transmission to humans.