Occurrence of anisakid parasites in marine fishes and whales off New Caledonia

Abstract

Anisakid nematodes are the most infamous parasites occurring in seafood with ability to infect humans. In the present study, the infective stages of five anisakid larval types, including Anisakis types I and III, Terranova types I and II and Contracaecum larval type, as well as adult Anisakis paggiae are reported from 16 host species from New Caledonian waters. The specific identity of the larval types was investigated using ITS sequence data. Anisakis larval types I and III were identified as Anisakis typica and Anisakis brevispiculata, respectively, based on identical ITS sequences. However, the specific identity of the Terranova larval types and Contracaecum larval type remains unknown until a matching ITS sequence from a well-identified adult is available. Several fish host species are reported for the first time for anisakid larval types found in this study. Considering that third-stage larvae of anisakids are known to be the infective stage of the parasite for humans and the popularity of seafood in New Caledonia, presence of these parasites in New Caledonian fish is of high importance in terms of public health and raising awareness among various stakeholders. Although adult nematodes in the present study were identified as Anisakis paggiae, the spicule length is shorter in our specimens and falls within the range reported for Anisakis oceanicus previously reported in Pacific waters from black fish (genus Globicephala) and later synonymised with Anisakis physeteris. However, our specimens are different from A. physeteris in morphology of ventriculus. Anisakis paggiae has been reported from whales in southern hemisphere and this is the first report from the Pacific regions.

Erection ofEuterranovan. gen. andNeoterranovan. gen. (Nematoda, Anisakidae), with the description ofE.dentiduplicatan. sp. and new records of two other anisakid nematodes from sharks off New Caledonia

“…The only adult anisakid nematode so far reported from elasmobranchs in New Caledonian waters is Terranova scoliodontis (Baylis, 1931), found in the tiger shark Galeocerdo cuvier (Péron et Lesueur) (Carcharhinidae) [29]. In the same region, unidentified larvae attributed to Terranova have been reported from different species of teleosts [22,37,38] and, based on sequence data, some of them were later identified as Terranova pectinolabiata Shamsi, Barton et Zhu, 2019 [35] or Pulchrascaris australis Shamsi, Barton et Zhu, 2020 [36].…”

Some adult and larval nematodes from fishes off New Caledonia

“…However, some of the fish species studied in the present study are known to harbour zoonotic nematodes. For example, Anisakis larval type I has been reported from Nemipterus furcosus (Valenciennes) and Saurida undosquamis (Richardson) in New Caledonian waters (Shamsi et al 2015;Shamsi et al 2018a). Nematode species reported in the present study may represent only a small sample of the diversity expected in the highly biodiverse range of hosts and parasite taxa in New Caledonian waters (Justine et al 2010a;Justine et al 2010b;Justine et al 2012a).…”

“…However, these studies have rarely focused primarily on nematodes which are considered to be of high zoonotic importance. The larval form of nematodes are difficult to accurately identify from morphology alone (Justine et al 2010a;Justine et al 2010b;Justine et al 2012a) and molecular studies are thus required, particularly for zoonotic marine ascaridoids (Shamsi et al 2015;Shamsi et al 2017;Shamsi et al 2018a). A more comprehensive understanding of host-parasite interactions is necessary to determine the overall and potential impact marine nematodes may have on wildlife and human health.…”

New records of anisakid nematodes from marine fishes off New Caledonia, with descriptions of five new species of Raphidascaris (Ichthyascaris) (Nematoda, Anisakidae)

“…is the first representative of the subgenus Ichthyascaris reported from a fish belonging to the aulopiform family Synodontidae. Larval anisakids were reported from this fish [25,27].…”

“…Moreover, an additional adult anisakid nematode not identified to species, reported as Raphidascaris (Ichthyascaris) sp., was recorded from Carangoides dinema Bleeker and C. fulvoguttatus (Forsskål) (Carangidae) [23]. Anisakid nematodes unidentified to species or genera, mostly as larval stages, have also been reported from fishes belonging to different families by Justine et al [10][11][12] and Shamsi et al [25][26][27].…”