On the occurrence and molecular identification of Contracaecum larvae (Nematoda: Anisakidae) in Mugil cephalus from Turkish waters

Ascaridoid parasites in European sardine throughout the annual cycle: Variability in parasitic load according to host stock features

In recent years, a drop in the condition of the European sardine has been observed. Although several causes have been attributed to this issue, as overfishing and climate change, little is known about the link between ascaridoid nematode parasitisation and fish status. In this study, sardines were obtained from four fishing grounds along the Mediterranean (Alboran, Northern Spain, Northern Adriatic, and Aegean), and one location in the Atlantic Ocean (Southern Portugal). After analysing individual fish body condition (by direct tissue fat content measurements and condition indices), and reproductive status (by a detailed gonadal examination) throughout the entire annual cycle, ascaridoids were recognised by combining naked eye and UV-press method along flesh, viscera, and gonads. Afterwards, sequence analysis of the rDNA internal transcribed spacers region (ITS) and the mtDNA cox2 gene were used to identify and characterise the different species of ascaridoids from the fish host in the localities throughout the seasons. The main species found along different areas was Hysterothylacium aduncum, present in the Northern Adriatic (prevalence of 7.6%, mean intensity 1.700), the Atlantic (7.5%, 3.889), and the Northern Spain (3.9%, 1.600). Moreover, few individuals of Anisakis simplex (s.s.) and A. pegreffii were observed in the Atlantic (1.7% and 0.8%, respectively), and the latter species was also found in the Adriatic stock (0.8%). All ascaridoid specimens were found in viscera. Obtained results seem to indicate that in stocks with medium sizes, small variations in length are related to parasite intensity. This study highlights the importance of seasonal parasitological analyses at stock level and, especially, in capital breeders, as relationships between condition and reproduction parameters and parasitism are conditioned by seasonality.

Ultramorphology and Molecular Studies of Contracaecum Larvae (Nematoda: Anisakidae) Collected in Five Cyprinid Fish Species from Sulaimani Province, Kurdistan Region-Iraq

A total of 1134 freshwater fishes belonging to Cyprinidae (Acanthobrama marmid (n=20), Alburnus caeruleus (n=7), Alburnus mossulensis (n=62), Arabibarbus grypus (n=123), Barbus lacerta (n=7), Capoeta trutta (n=222), C. umbla (n=161), Carasobarbus kosswigi (n=5), C. luteus (n=89), Carassius auratus (n=54), Chondrostoma regium (n=52), Cyprinion kais (n=10) and C. macrostomum (n=322)) were collected in different water bodies in Sulaimani Province, Kurdistan Region-Iraq for the presence of larval nematode of the genus Conteacaecum. This investigation revealed that 17 fishes belonged to five species (A. marmid, A. grypus, C. trutta, C. luteus and C. regium) were infected with Contracaecum larvae with prevalence of 35 %, 0.81 %, 0.90 %, 4.49 % and 5.76 %, respectively. The third- larval stage was morphologically studied by optical microscopy, and the ultrastructure was investigated using scanning electron microscopy (SEM). In addition, molecular analysis was carried out by amplifying, sequencing and comparing different gene loci, including internal transcribed spacers (ITS-1 and ITS-2) and cytochrome oxidase c subunit-II (COX-2), of the different isolated Contracaecum larvae. These sequences were also compared with closely related nematode sequences from the GenBank. Fifteen sequences were obtained for this study from the collected Contracaecum larvae. ITS-1, ITS-2 and COX-2 were amplified by polymerase chain reaction (PCR) and sequenced. The sequences of ITS-1, ITS-2 and COX-2 revealed that the collected Contracaecum larval specimens from all infected fish species represented one species (Contracaecum rudolphii B) based on the identity percentage in the GenBank database. The genetic characterisation of the parasite in the present study is available in the GenBank database, and the obtained ITS-1, ITS-2 and COX-2 sequences were deposited in GenBank. The present study provides information on the accurate identification and molecular analysis of Contracaecum larvae in the infected fish species in Sulaimani Province, Kurdistan Region-Iraq.

Genera and Species of the Anisakidae Family and Their Geographical Distribution

Simple Summary

The parasites of the Anisakidae family infest mainly marine mammals; however, they have the ability to infest paratenic hosts such as mollusks, small crustaceans and fish. The consumption of meat from animals of aquatic origin favors the acquisition of the disease known as Anisakiasis or Anisakidosis, depending on the species of the infecting parasite. Currently, the identification of the members of this family is carried out through the use of molecular tests, which brings about the generation of new information. The purpose of this review was to identify the genus and species of the Anisakidae family by reviewing scientific papers that used molecular tests to confirm the genus and species. The adaptability of the Anisakidae family to multiple hosts and environmental conditions allows it to have a worldwide distribution. As it is a zoonotic agent and causes non-specific clinical symptoms, it is important to know about the different members of the Anisakidae family, as well as the hosts where they have been collected.

Abstract

Nematodes of the Anisakidae family have the ability to infest a wide variety of aquatic hosts during the development of their larval stages, mainly marine mammals, aquatic birds, such as pelicans, and freshwater fish, such crucian carp, these being the hosts where the life cycle is completed. The participation of intermediate hosts such as cephalopods, shrimp, crustaceans and marine fish, is an important part of this cycle. Due to morphological changes and updates to the genetic information of the different members of the family, the purpose of this review was to carry out a bibliographic search of the genus and species of the Anisakidae family identified by molecular tests, as well as the geographical area in which they were collected. The Anisakidae family is made up of eight different parasitic genera and 46 different species. Those of clinical importance to human health are highlighted: Anisakis pegreffi, A. simplexsensu stricto, Contracaecumosculatum, Pseudoterranova azarazi, P. cattani, P. decipiens and P. krabbei. The geographical distribution of these genera and species is located mainly in the European continent, Asia and South America, as well as in North and Central America and Australia. Based on the information collected from the Anisakidae family, it was determined that the geographical distribution is affected by different environmental factors, the host and the ability of the parasite itself to adapt. Its ability to adapt to the human organism has led to it being considered as a zoonotic agent. The disease in humans manifests nonspecifically, however the consumption of raw or semi-raw seafood is crucial information to link the presentation of the parasite with the disease. The use of morphological and molecular tests is of utmost importance for the correct diagnosis of the genus and species of the Anisakidae family.

A new species of Contracaecum (Nematoda: Anisakidae) found parasitizing Nannopterum brasilianus (Suliformes: Phalacrocoracidae) and Hoplias argentinensis (Characiformes: Erythrinidae) in South America: morphological and molecular characterization of larval and adult stages

Nematode species of the genus Contracaecum Railliet & Henry, 1912 have been reported around the world in many species of fish-eating birds and seals. Here, Contracaecum jorgei n. sp. is morphologically described using light and scanning electron microscopy for adults and fourth-stage larvae (L4) found in the bird Nannopterum brasilianus and third-stage larvae (L3) found in the freshwater fish Hoplias argentinensis, both from the province of Córdoba, Argentina. Additionally, sequences of cytochrome c oxidase subunit II were obtained from these specimens and molecular phylogenetic analysis was used to determine its relationships within the genus. The present species is distinguished from other species by the number and disposition of cephalic papillae; shape and size of the interlabia; length of the spicules; and number and arrangement of papillae in the posterior end of the male. Furthermore, in the molecular analyses, sequences obtained from adult L4 and L3 specimens of C. jorgei n. sp. were similar and grouped, forming an independent lineage, thus confirming it as a distinct species. Thus, morphological characteristics associated with molecular data support the proposal of a new species.

Species of Anisakidae nematodes and Clinostomum spp. infecting lisa Mugil curema (Mugilidae) intended for human consumption in Mexico

Anisakisspp. nematodes are potentially zoonotic parasites; that infects a wide variety of aquatic species worldwide, with marine fish being the paratenic hosts. The aim of study was identify the presence of Anisakidae nematodes, and other parasites in Mugil curema . A total of 96 M . curema obtained from local markets in Tulancingo, Hidalgo, Mexico, were analyzed by necropsy. Only five M . curema present nematode collection in epaxial muscle. The tissues with the highest prevalence of parasites were identified, and samples of epaxial muscle with larval migration analyzed by histopathology. Visible parasites in necropsy tissues were classified according to their morphology. Nematode found in the liver were Contracaecum spp. (41.17%) and Pseudoterranova spp. third stage (7.36%); in the caudal part of the kidney were Anisakis spp. (13.23%), Pseudoterranova spp. third stage (11.77%) and Contracaecum spp. (5.88%); and in epaxial muscle were Anisakis spp. Larva I (5.88%) and Pseudoterranova spp (4.42%). In one fish, Clinostomum spp. was detected in epaxial caudal muscle. The present work reports for the first time the presence of nematodes of the family Anisakidae and Clinostonum spp. metacercariae, with zoonotic potential, in M . curema intended for human consumption in Tulancingo, Hidalgo, Mexico.