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

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.

Occurrence of ascaridoid nematodes in selected edible fish from the Persian Gulf and description of Hysterothylacium larval type XV and Hysterothylacium persicum n. sp. (Nematoda: Raphidascarididae).

Despite several reports on the presence of the potentially zoonotic nematodes among edible fishes in the Persian Gulf, there is still no study on the specific identification of these parasites or their genetic characterisation. In the present study, a total of 600 fish belonging to five popular species of fish in the region, including Otolithes ruber, Psettodes erumei, Saurida tumbil, Scomberomorus commerson and Sphyraena jello were examined for infection with nematode parasites. Detailed microscopy of nematodes found in the present study followed by characterisation of the first and second internal transcribed spacers (ITS-1 and ITS-2, respectively) showed that they belong to five distinct taxa that could be potentially zoonotic. Anisakis type I was found in four species of fish, had identical ITS sequences as Anisakis typica previously reported in Australian waters and was different from those reported in the Nearctic. Hysterothylacium type VI in the present study was morphologically similar to those previously described from Australasian waters and ITS sequences were identical among Australian specimens and those found in the present study. Another Hysterothylacium larval type was also found in the present study which had identical ITS sequences and similar morphology to those previously reported and identified as H. amoyense in China Sea. Since no ITS sequence data from a well identified adult H. amoyense with an identifiable museum voucher number is yet available and due to some other issues discussed in the article we suggest assignment of this larval type from the China Sea and the Persian Gulf to H. amoyense is doubtful until future studies on a well identified male specimen of H. amoyense or other species reveals the specific identity of this larval type. We propose to refer to this larval type as Hysterothylacium larval type XV. In the present study we also describe a new species, Hysterothylacium persicum and discuss how to differentiate it from closely related species. We also found some adult females with distinct morphology and ITS sequence but due to lack of male specimens they have been referred as Hysterothylacium sp. in this paper. They had the same ITS sequence data as Hysterothylacium larval type VI. This study shows the presence of a relatively broad diversity of potentially zoonotic nematodes in edible fish of the Persian Gulf. Therefore educational campaigns for public and local health practitioners are suggested to protect consumers from becoming infected with these parasites.